Self-mixing interferometry using back-emitting VCSEL diodes with integrated photodetectors

Abstract

To provide an optoelectronic sensing device having a vertical cavity surface emitting laser (VCSEL), a resonant cavity photodetector (RCPD), and a tunnel junction.SOLUTION: VCSEL is at least partially defined by a first set of semiconductor layers disposed on a substrate. The first set of semiconductor layers includes a first active region. The VCSEL is configured to emit laser light toward a substrate upon application of a first bias voltage and experience self-mixing interference upon reception of reflected or backscattered light, and RCPD is at least partially defined by a second set of semiconductor layers that are disposed on the substrate to be vertically adjacent to the VCSEL. The second set of semiconductor layers include a second active region. The RCPD is configured to detect self-mixing interference upon application of a second bias voltage. The tunnel junction is disposed between the first active region and the second active region.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Cross-reference of related applications This application is non-provisional and claims interest under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63 / 540,253, filed September 25, 2023, the contents of which are incorporated herein by reference as if they were fully disclosed herein.

[0002] The embodiments described relate generally to light sensing, and more specifically to light sensing based on self-mixing interferometry (SMI). [Background technology]

[0003] Electronic devices may include photoelectronic sensors. For example, photoelectronic sensors may be included in portable electronic devices such as mobile phones, tablet computers, laptop computers, cameras, portable music players, mobile terminals, vehicle navigation systems, robotic navigation systems, electronic watches, health or fitness tracking devices, and other portable or mobile devices. Photoelectronic sensors may also be included in devices that are semi-permanently located (or installed) in a single location (e.g., security cameras, doorbells, door locks, thermostats, refrigerators, or other equipment). Some of these electronic devices may include one or more input elements or surfaces, such as cameras, buttons, or touchscreens, that allow a user to input commands or data via touch, press, gesture, or image. The touch, press, gesture, or image may be detected by components of the electronic device (e.g., one or more photoelectronic sensors) that detect presence, distance, location, motion, topology, or other parameters. The same and / or other electronic devices may similarly or alternatively include one or more sensors that sense proximity, distance, particle velocity, or other parameters without receiving intentional user input.

[0004] Some photoelectronic sensors may include a light source (e.g., a laser) that emits a beam of light toward or through the input surface. The distance, location, motion, topology, or other parameters of an object on or opposite the input surface can be inferred from the reflection or backscatter of the emitted light from the input surface and / or the object.

[0005] Some photoelectronic sensors may include vertical-cavity surface-emitting laser (VCSEL) diodes. VCSEL diodes can undergo self-mixing interference, in which case the reflected laser light they emit is received back into their resonant cavity. Self-mixing interference can induce a shift in the properties of the laser light generated within the resonant cavity, such as wavelength, to a state different from that in the absence of received reflection ("free emission"). If the received reflection originates from an input surface or object, the shift in properties may correlate, for example, with the displacement, distance, motion, speed, or velocity of the input surface or object that caused the reflection. [Overview of the Initiative]

[0006] The term "embodiment" and similar terms, such as "implementation," "configuration," "aspect," "example," and "option," are intended to broadly refer to all of the subject matter of this disclosure and the following claims. Descriptions containing these terms should be understood not to limit the subject matter described herein, nor to limit the meaning or scope of the following claims. The embodiments of this disclosure as incorporated herein are defined by the following claims, not by the summary of the invention. The summary of the invention is a high-level overview of the various aspects of this disclosure and introduces some of the concepts further described in the sections on embodiments for carrying out the invention. This summary is not intended to identify the main or essential features of the claimed subject matter. Nor is this summary intended to be used alone to determine the scope of the claimed subject matter. The subject matter should be understood by referring to the entire specification of this disclosure, any or all of the drawings, and the appropriate portions of each claim.

[0007] Embodiments of the present disclosure relate to a photoelectron sensing device having a vertical-cavity surface-emitting laser (VCSEL), a resonant cavity photodetector (RCPD), and a tunnel junction. The VCSEL is at least partially defined by a first set of semiconductor layers disposed on a substrate. The first set of semiconductor layers includes a first active region. The VCSEL is configured to emit laser light toward the substrate when a first bias voltage is applied and to undergo self-mixing interference when receiving reflection or backscatter of laser light emitted from a target object. The RCPD is at least partially defined by a second set of semiconductor layers disposed on the substrate perpendicularly adjacent to the VCSEL. The second set of semiconductor layers includes a second active region. The RCPD is configured to detect self-mixing interference during laser light emission by the VCSEL when a second bias voltage is applied. The tunnel junction is located between the first active region and the second active region.

[0008] Embodiments of the present disclosure further relate to a photoelectron sensing device having a substrate, a pair of conductive layers, and a lattice structure disposed on a pair of multilayer semiconductor layers. The substrate has a front surface and a back surface. The pair of multilayer semiconductor layers are disposed on the front surface and define a vertical-cavity surface-emitting laser (VCSEL) and a resonant cavity photodetector (RCPD). The VCSEL has a first active region within its resonant cavity. The VCSEL is configured to emit primary radiation toward the substrate through the back surface when a first bias voltage is applied. The RCPD has a second active region offset from the first active region.

[0009] Embodiments of the present disclosure also relate to a photoelectron sensing device having a substrate, a pair of multilayer semiconductor layers, and at least one conductor. The substrate has a front surface and a back surface. The pair of multilayer semiconductor layers are arranged on the front surface and define a pair of mesas. The pair of mesas includes one or more mesas of a first pair and one or more mesas of a second pair. Each mesa in one or more mesas of the first pair includes a vertical-cavity surface-emitting laser (VCSEL) and a resonant cavity photodetector (RCPD). The VCSEL has a first active region within its resonant cavity. The VCSEL is configured to emit primary radiation toward the substrate through its back surface when a first bias voltage is applied. The RCPD has a second active region offset from the first active region. When a second bias voltage is applied, the RCPD is configured to detect self-mixing interference of the primary radiation in the laser cavity of the VCSEL upon reception of reflection or backscatter. A photoelectronic sensing device comprising: at least one conductor electrically connected to the elements of a first mesa in one or more mesas of a first set and routed over a portion of a second mesa in one or more mesas of a second set.

[0010] The above summary is not intended to represent any or all embodiments of the present disclosure. Rather, the above summary of the invention merely provides some examples of novel embodiments and features described herein. The above features and advantages of the present disclosure, as well as other features and advantages, will be readily apparent from the following detailed description of representative embodiments and forms for carrying out the invention in relation to the accompanying drawings and the accompanying claims. Additional embodiments of the present disclosure will be apparent to those skilled in the art with reference to the detailed description of various embodiments, which are provided below.

[0011] The disclosure will be easily understood by the following detailed description, along with the attached drawings in which similar reference numbers specify similar structural elements. [Brief explanation of the drawing]

[0012] [Figure 1]This is a cross-sectional view of a first exemplary structure of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode integrated with a resonant cavity photodetector (RCPD) according to some aspects of the present disclosure, wherein the RCPD is positioned away from the primary emission of the VCSEL diode.

[0013] [Figure 2] This is a cross-sectional view of a second exemplary structure of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode integrated with a resonant cavity photodetector (RCPD) according to some aspects of the present disclosure, wherein the RCPD is positioned along the primary emission of the VCSEL diode.

[0014] [Figure 3] Figure 1 shows a cross-sectional view of an exemplary photoelectron sensing device having a first exemplary structure of a back-emitting VCSEL diode integrated with an RCPD, according to several aspects of this disclosure.

[0015] [Figure 4] The following are cross-sectional views of lattice structures configured to be arranged on a set of multilayer semiconductor layers on a substrate forming an exemplary photoelectron sensing device, according to some aspects of the present disclosure.

[0016] [Figure 5A] Figure 4 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has a cathode load or an anode drive, according to several aspects of this disclosure. [Figure 5B] Figure 4 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has a cathode load or an anode drive, according to several aspects of this disclosure. [Figure 5C] Figure 4 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has a cathode load or an anode drive, according to several aspects of this disclosure. [Figure 5D]Figure 4 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has a cathode load or an anode drive, according to several aspects of this disclosure.

[0017] [Figure 6] Figure 4 shows a schematic diagram of the operating circuit in an exemplary photoelectronic sensing device in which the bias polarity of the RCPD is switched in the time domain, according to some aspects of the present disclosure.

[0018] [Figure 7] Figure 2 shows a cross-sectional view of an exemplary photoelectron sensing device having a second exemplary structure of a back-emitting VCSEL diode integrated with an RCPD, according to several aspects of this disclosure.

[0019] [Figure 8A] Figure 7 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has anode drive or cathode load, according to some aspects of the present disclosure. [Figure 8B] Figure 7 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has anode drive or cathode load, according to some aspects of the present disclosure. [Figure 8C] Figure 7 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has anode drive or cathode load, according to some aspects of the present disclosure. [Figure 8D] Figure 7 shows schematic diagrams of the operating circuits in an exemplary photoelectronic sensing device, depending on whether the back-emitting VCSEL diode has anode drive or cathode load, according to some aspects of the present disclosure.

[0020] [Figure 9A]The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectron sensing device having a resonant cavity extended to the radiating side of a back-emitting VCSEL diode with a multi-junction structure within the photoelectron sensing device, according to several aspects of the present disclosure. [Figure 9B] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectron sensing device having a resonant cavity extended to the radiating side of a back-emitting VCSEL diode with a multi-junction structure within the photoelectron sensing device, according to several aspects of the present disclosure.

[0021] [Figure 10A] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectronic sensing device having a plurality of sets of back-emitting VCSEL diodes integrated with an RCPD, and having a first arrangement of electrical connections between the plurality of sets, respectively, according to some aspects of the present disclosure. [Figure 10B] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectronic sensing device having a plurality of sets of back-emitting VCSEL diodes integrated with an RCPD, and having a first arrangement of electrical connections between the plurality of sets, respectively, according to some aspects of the present disclosure.

[0022] [Figure 11A] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD, and having a second arrangement of electrical connections between the multiple sets, according to some aspects of the present disclosure. [Figure 11B] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectronic sensing device having multiple sets of back-emitting VCSEL diodes integrated with an RCPD, and having a second arrangement of electrical connections between the multiple sets, according to some aspects of the present disclosure.

[0023] [Figure 12A]The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectron sensing device having a resonant cavity extended to the radiating side of a back-emitting VCSEL diode with a multi-junction structure within the photoelectron sensing device, according to several aspects of the present disclosure. [Figure 12B] The following are cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectron sensing device having a resonant cavity extended to the radiating side of a back-emitting VCSEL diode with a multi-junction structure within the photoelectron sensing device, according to several aspects of the present disclosure.

[0024] [Figure 13A] Perspective views and corresponding cross-sectional views of a first exemplary set of photoelectron sensing devices, such as a set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or 12A-12B, are shown, respectively. [Figure 13B] Perspective views and corresponding cross-sectional views of a first exemplary set of photoelectron sensing devices, such as a set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or 12A-12B, are shown, respectively.

[0025] [Figure 14] A top view of an exemplary array of photoelectron sensing devices, as illustrated and described with reference to Figures 13A to 13B, is shown.

[0026] [Figure 15A] Perspective views and corresponding cross-sectional views of a second exemplary set of photoelectron sensing devices, such as a set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or 12A-12B, are shown, respectively. [Figure 15B] Perspective views and corresponding cross-sectional views of a second exemplary set of photoelectron sensing devices, such as a set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or 12A-12B, are shown, respectively.

[0027] [Figure 16] A top view of an exemplary array of photoelectron sensing devices, as illustrated and described with reference to Figures 15A and 15B, is shown.

[0028] [Figure 17] This is a top view of a first exemplary layout of a photoelectron sensing device, such as a photoelectron sensing device, as illustrated and described with reference to Figures 9A-9B or 12A-12B.

[0029] [Figure 18] This is a top view of a second exemplary layout of a photoelectron sensing device, such as a photoelectron sensing device, as illustrated and described with reference to Figures 9A-9B or 12A-12B.

[0030] [Figure 19] This is a top view of the first array of a second exemplary layout of a photoelectron sensing device, as shown and described with reference to Figure 18.

[0031] [Figure 20] This is a top view of a second array of a second exemplary layout of a photoelectron sensing device, shown and described with reference to Figure 18.

[0032] [Figure 21] The following are illustrative electrical block diagrams of electronic devices having photoelectronic sensors according to some aspects of this disclosure.

[0033] The use of cross-hatching or shading in the attached diagrams is generally provided to clarify the boundaries between adjacent elements and to enhance the visibility of the diagrams. Therefore, neither the presence nor absence of cross-hatching or shading conveys or indicates any preference or requirement for any particular material, material properties, element ratios, element dimensions, commonalities of the illustrated elements, or any other characteristics, attributes, or properties of any element shown in the attached diagrams.

[0034] While various modifications and alternative forms are possible with respect to this disclosure, specific embodiments are shown in the drawings as examples and described in detail herein. However, it should be understood that the invention is not limited to the specific forms disclosed. Rather, this disclosure encompasses all modifications, equivalents, and alternatives that fall within the spirit and scope of the invention as defined by the appended claims.

[0035] Additionally, the proportions and dimensions (relative or absolute) of various features and elements (and their sets and groups), as well as the boundaries, separation points and positional relationships presented between them, are provided in the accompanying figures solely to facilitate understanding of the various embodiments described herein and are therefore not necessarily presented or illustrated to a specific scale. It should be understood that there is no intention to present any preferences or requirements for the illustrated embodiments by excluding the embodiments described therein. [Modes for carrying out the invention]

[0036] Various embodiments are described with reference to the accompanying drawings, and similar reference numerals are used throughout the drawings to designate similar or equivalent elements. The drawings are not necessarily drawn to a specific scale and are provided solely to illustrate the aspects and features of the disclosure. Numerous specific details, relationships, and methods are described to provide a complete understanding of some aspects and features of the disclosure, but those skilled in the art will recognize that these aspects and features may be implemented using other relationships or other methods without using one or more of the specific details. In some examples, well-known structures or operations are not shown in detail for illustrative purposes. The various embodiments disclosed herein are not necessarily limited to the illustrated order of operations or events, as some operations may occur in a different order and / or simultaneously with other operations or events. Furthermore, not all illustrated operations or events are necessarily required to implement certain aspects and features of the disclosure.

[0037] For the purposes of this detailed explanation, unless otherwise specified, singular forms include plural forms where appropriate, and vice versa. The word “includes” means “includes without limitation.” Furthermore, approximations such as “about,” “almost,” “substantially,” and “approximately” may be used herein to mean “in,” “near,” “almost,” “within 3-5% of,” “within acceptable manufacturing tolerances,” or any logical combination thereof. Similarly, the terms “vertical” or “horizontal” are intended to further include “within 3-5%” in the vertical or horizontal direction, respectively.

[0038] Furthermore, directional terms such as “top,” “bottom,” “upper,” “lower,” “front,” “back,” “over,” “under,” “above,” “below,” “left,” and “right” are used with reference to some orientations of components in some of the drawings described below. Since components in various embodiments may be arranged in many different orientations, the directional terms are used for illustrative purposes only and are not limiting in any sense. The directional terms are intended to be interpreted broadly and should not be interpreted as excluding components arranged in different ways. These terms are intended to relate to orientations equivalent to those depicted in the reference drawings and are understood in context from the referenced object(s) or element(s), for example, from a position commonly used for an object(s) or element(s), or as otherwise described herein. Furthermore, it should be noted that the term "signal" refers to any waveform that can travel through a medium (e.g., electrical, optical, magnetic, mechanical, or electromagnetic), such as DC, AC, sine waves, triangular waves, square waves, and vibrations.

[0039] Furthermore, when used herein, the phrase “at least one” preceding a set of items, along with the terms “and” or “or” separating any of the items, qualifies the list as a whole, rather than each individual element of the list. The phrase “at least one” does not require the selection of at least one of each item listed; rather, it allows for the meaning of including at least one of any of the items, and / or at least one of any combination of items, and / or at least one of each of the items. For example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” refer, respectively, to A only, B only, or C only, any combination of A, B, and C, and / or one or more of each of A, B, and C. Similarly, it should be understood that the order of elements presented for combined or separated lists provided herein should not be construed as limiting this disclosure to only that order.

[0040] The embodiments described herein concern photoelectron sensing devices, such as those that can be used for touch or input sensors, proximity or particle sensors, or other types of sensors, and their structures. Such photoelectron sensing devices may use one or more VCSEL diodes having integrated photodiodes, such as resonant cavity photodiodes (RCPDs), that receive laser light emitted from back-emitting vertical-cavity surface-emitting laser (VCSEL) diodes. Electronic devices may use such photoelectron sensing devices as part of a system for detecting the displacement, distance, motion, speed, or velocity of an object (or "target"). Such an object may be a component of the electronic device, such as an input surface or touchpad, or the target may be outside the electronic device. For example, a photoelectron sensing device may be part of a camera's autofocus system and may be used to detect the distance to an external object or the motion of an external object. Hereinafter, for convenience, all such possible measured kinematic parameters of a target will simply be referred to as "distance or motion".

[0041] In a back-emitting VCSEL diode, laser light is generally emitted from a resonant cavity containing at least one active region (a pn junction surrounding the laser cavity) through the substrate on which the back-emitting VCSEL diode is formed. Reflections of the emitted laser light are received back into the resonant cavity, potentially inducing self-mixing interference, which alters the properties of the laser light, such as wavelength, from values ​​they would have without the reflection. The change in properties can then be correlated with the distance or movement of the object causing the reflection.

[0042] One way the altered characteristics can be detected is through a change in one or more electrical properties of the back-emitting VCSEL diode itself, such as voltage, current, or power. Alternatively, the altered emitted laser light may be received by a photodiode associated with the back-emitting VCSEL diode, the photodiode having output parameters related to the altered characteristics of the self-mixed emitted laser light of the VCSEL diode.

[0043] In various embodiments described herein, a back-emitting VCSEL diode can be configured, when forward-biased, to emit primary radiation from an active region toward an object through the emitting side of a photoelectron sensing device and toward a photodiode integrated inside. The change in the properties of the laser light due to self-mixing with reflection from the object is present in the primary radiation received by the photodiode, and when the photodiode is reverse-biased, it can generate measurable electrical parameters having values ​​related to the changed properties of the primary radiation, from which the distance or motion of the object can be inferred.

[0044] In some embodiments described herein, the photodiode is integrally formed on a semiconductor substrate, for example, using epitaxial deposition techniques, and a VCSEL is formed thereon. The photodiode may be positioned between the semiconductor substrate and the VCSEL diode, or the VCSEL diode may be positioned between the semiconductor substrate and the photodiode. Various electrical connections can be formed in or on the substrate, VCSEL diode, and / or photodiode, for example, to bias the VCSEL diode, to receive signals from the photodiode, or to receive other electrical signals. The VCSEL diode may have a modulated input current (or voltage) to provide modulation of the primary radiation. Such modulation of the primary radiation may allow for estimation of the distance and motion of a target.

[0045] To improve the absorption efficiency of primary radiation into the laser cavity of a VCSEL diode, additional photodetector structures, such as one or more gain stage layers including, but not limited to, indium gallium arsenide (InGaAs) layers and aluminum gallium arsenide (AlGaAs) layers, can be formed within the resonant cavity of the VCSEL diode. Furthermore, depending on the polarity of the junction, a tunnel junction can be inserted between the photodiode junction of the photodiode and the laser junction of the VCSEL diode to improve carrier injection and extraction and reduce the operating voltage of the photoelectron sensing device.

[0046] In some embodiments, a multi-junction structure consisting of multiple active regions (e.g., multiple pairs of barrier layers alternating with quantum well layers) and highly doped tunnel junctions scattered between them can be vertically stacked within the resonant cavity of a VCSEL diode. The multi-junction structure may have one or more oxide layers formed at the top, bottom, or middle. Such a multi-junction (MJ) VCSEL diode can emit laser light with different characteristics than those emitted by an equivalent single-junction (SJ) VCSEL diode operating at a similar current level. The multi-junction structure allows the MJ VCSEL diode to operate at an increased voltage level (compared to a similar SJ VCSEL diode operating at a similar current level), which can provide several factors for increasing the output power gain, for example. It can also increase the center frequency of the emitted laser light, thereby reducing 1 / f noise and improving the signal-to-noise ratio (SNR). The increased SNR and higher operating frequency also enable improved spatial resolution of targets by photoelectronic sensing devices utilizing MJ VCSEL diodes, due to the increased efficiency and adjustable range for wavelength modulation of the emitted laser light by the MJ VCSEL diodes. This, in turn, allows for better measurement of electrical parameters related to the self-mixing interference of the emitted laser light. Thus, multi-junction structures improve the performance of photoelectronic sensing devices through faster signal transmission, wider sampling, and reduced complexity.

[0047] In some embodiments, the photoelectron sensing device having a multi-junction structure may also include an extended resonant cavity extending from the VCSEL diode to an on-chip lens (OCL) formed at the rear end of the substrate, and the substrate itself. The extended resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-range sensing.

[0048] In some embodiments, the photoelectron sensing device may have a semiconductor wafer or chip disposed on its surface and defining a set of mesas, at least some of which include a VCSEL diode having an integrated photodiode. The VCSEL diode is configured, when forward-biased, to emit primary laser light from an active region surrounding its laser cavity toward the substrate, through its back surface. The photodiode may be an RCPD having an active region offset from the active region of the VCSEL diode. The RCPD is configured, when reverse-biased, to detect self-mixing interference of primary radiation upon reception of reflection or backscatter of primary radiation. Adjacent mesas are connected to a power supply and connected to each other via one or more conductors.

[0049] While specific photoelectron sensing devices are shown in the figures and described below, the embodiments described herein, without limitation, may be used with a variety of electronic devices, including mobile phones, personal digital assistants, timing devices, health monitoring devices, wearable electronic devices, input devices (e.g., styluses), desktop computers, and electronic glasses. Although a variety of electronic devices are mentioned, the photoelectron sensing devices of this disclosure may also be used with other products and combined with a variety of materials.

[0050] These embodiments and other embodiments will be described below with reference to Figures 1 to 12. However, those skilled in the art will readily understand that the embodiments for carrying out the invention given herein with respect to these figures are for illustrative purposes only and should not be construed as limiting.

[0051] Figure 1 shows a cross-sectional view of a first exemplary structure 100 of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode 120 integrated with a resonant cavity photodetector (RCPD) 130, where the RCPD 130 is positioned in the path of secondary emission away from the primary emission 140 of the VCSEL diode 120. The VCSEL diode 120 is formed on a semiconductor substrate 110 by an epitaxial deposition technique or the like. The VCSEL diode 120 includes a first active region 128 having one or more quantum well structures. The first active region 128 forms a highly doped pn junction, which, when forward-biased, allows charge carriers to traverse the pn junction and induce the primary emission 140 of laser light toward the substrate 110. Distributed Bragg diffraction layers, formed as alternating high-refractive-index and low-refractive-index semiconductor layers, are present on both sides of the first active region 128 and can function as mirrors within the resonant cavity of the VCSEL diode 120.

[0052] When this primary radiation 140 is reflected and backscattered from the target object 150, it is received into the laser cavity of the first active region 128, where it undergoes self-mixing interference. As a result, the electrical properties of the VCSEL diode 120 and / or the primary radiation 140 are altered.

[0053] The RCPD 130 is formed on the VCSEL diode 120 by epitaxial deposition technology or the like and includes a second active region 138. The RCPD 130 receives the laser light of the VCSEL diode 120, whose electrical properties have been altered. The second active region 138 is configured to detect the altered electrical properties of the self-mixed laser light of the VCSEL diode 120 when reverse-biased and to generate an output signal that depends on the wavelength of the self-mixed primary emission of the VCSEL diode 120. The distance or movement of a target object 150 that reflects or backscatters the primary emission 140 can be determined based on the output signal from the RCPD 130.

[0054] Figure 2 shows a cross-sectional view of a second exemplary structure 200 of a back-emitting vertical-cavity surface-emitting laser (VCSEL) diode 220 integrated with a resonant cavity photodetector (RCPD) 130, where the RCPD 230 is positioned along the primary emission 240 of the VCSEL diode 220.

[0055] The RCPD 230 is formed on the semiconductor substrate 210 by epitaxial deposition or the like, and includes a first active region 238. The VCSEL diode 220 is also formed on the RCPD 230 by epitaxial deposition. The VCSEL diode 220 includes a second active region 228 having one or more quantum well structures. The second active region 228 forms a highly doped pn junction, which, when forward biased, allows charge carriers to traverse the pn junction and induce primary emission 240 of laser light toward the substrate 210. Distributed Bragg diffraction layers, formed as alternating semiconductor layers of high and low refractive indices, are present on both sides of the second active region 228 and can function as mirrors within the resonant cavity of the VCSEL diode 220.

[0056] When this primary radiation 240 is reflected and backscattered from the target object 250, it is received in the laser cavity of the second active region 228, where it undergoes self-mixing interference. As a result, the electrical properties of the VCSEL diode 220 and / or the primary radiation 240 are altered.

[0057] Furthermore, the RCPD 230 receives the laser light from the VCSEL diode 220, whose electrical characteristics have been altered. The first active region 238 is configured to detect the altered electrical characteristics of the self-mixed laser light of the VCSEL diode 220 when reverse-biased and to generate an output signal that depends on the wavelength of the self-mixed primary emission 240 of the VCSEL diode 220. Based on the output signal from the RCPD 230, the distance or movement of the target object 250 receiving the primary emission 240 can be determined.

[0058] Figure 3 shows a cross-sectional view of an exemplary photoelectron sensing device 300 having a first exemplary structure 100 of a back-emitting VCSEL diode integrated with an RCPD (shown in Figure 1). In particular, the back-emitting VCSEL diode 302 is integrated with an RCPD 312 that, under forward bias, is positioned in the path of secondary radiation, away from the primary radiation 340 generated from the VCSEL diode 302. The RCPD 312 receives the modified primary radiation from the VCSEL diode 302 after the primary radiation 340 has undergone self-mixing interference when receiving reflections or backscatters within it.

[0059] The photoelectron sensing device 300 is fabricated by first depositing a set of multilayer semiconductor layers on the surface 308f of the substrate 308 to form a VCSEL diode 302, and then forming an RCPD 312 on the VCSEL diode 302. The on-chip lens 330 is positioned on the rear surface 308r of the substrate 308 and is configured to collimate, focus, or amplify the laser light emitted by the VCSEL diode 302, and to collect the return laser light that comes back into the laser cavity of the first active region 302 within the VCSEL diode 302 for coherent mixing.

[0060] The VCSEL diode 302 may include a radiation-side (or "upper") distributed Bragg reflector (hereinafter "DBR") layer 303a that functions as a first (or "radiating-side") mirror of the laser structure. The radiation-side DBR layer 303a may include a pair of alternating materials having different refractive indices. Each such pair of alternating materials is referred to herein as a Bragg pair. One or more materials in the radiation-side DBR layer 303a may be doped to be p-type and thus form part of the anode portion of the pn diode junction of the VCSEL diode 302. An exemplary pair of materials that may be used to form the radiation-side DBR layer 303a is aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs).

[0061] The VCSEL diode 302 can also include a base-side DBR layer 303b that functions as the second (or "base side" or "bottom side") mirror of the laser. The base-side DBR layer 303b can also include a set of Bragg pairs of alternating materials having different refractive indices. One or more materials within the base-side DBR layer 303b may be doped to be n-type and thus form part of the cathode portion of the p-n diode structure. Exemplary pairs of materials that can be used to form the base-side DBR layer 303b are aluminum arsenide (AlAs) and GaAs.

[0062] In some embodiments, the DBR layers 303a and 303b may be formed from semiconductor epitaxy and either semiconductor GaAs, AlxGa1-xAs for (0 < x ≤ 1), or other semiconductor materials. In other embodiments, the DBR layers 303a and 303b may be formed from dielectric materials. Examples of such dielectrics include, but are not limited to, amorphous silicon (a-Si), silicon dioxide (SiO2), SiO2 / niobium pentoxide (Nb2O5), and SiO2 / tantalum pentoxide (Ta2O5). In still other embodiments, the DBR layers 303a and 303b may be formed as a hybrid of semiconductor materials and dielectric materials.

[0063] The VCSEL diode 302 can include an active region 307 that functions partially as a resonant cavity. In a laser diode such as the VCSEL diode 302, the active region 307 can include one or more quantum wells. In some embodiments as shown in FIG. 3, the active region 307 of the VCSEL diode 302 may be adjacent to an oxide layer 309 having an aperture through which primary emission 340 escapes. In some embodiments as shown in FIG. 3, the active region 307 further includes one or more gain layers 304 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the VCSEL diode 302 to improve the absorption efficiency of the primary emission 340.

[0064] The VCSEL diode 302 can be formed by epitaxial growth of layers for each of the following: the radiating layer 303a, the base-side DBR layer 303b, the active region 307, and the oxide layer 309, and optionally other layers. These various layers can be formed by epitaxial growth on the substrate 308. The power supply contacts 305a and 305b can be formed on the radiating layer and the base-side layer of the VCSEL diode 302.

[0065] The RCPD 312 is formed on the VCSEL diode 302. In some embodiments, the RCPD 312 may include an active region 314 (offset from the active region 307 of the VCSEL diode 302) and a power supply contact 315a. The active region 314 may include one or more gain layers (e.g., an InGaAs layer, an AlGaAs layer) to improve the absorption efficiency of the altered primary radiation 340 after it has undergone self-mixing interference within the active region 307 of the VCSEL diode 302. The power supply contact 315a forms a ring or horseshoe-shaped connection on the upper side of the RCPD 312. The lattice structure 320 may be arranged perpendicularly on a set of multilayer semiconductor layers forming the RCPD 312, as will be further described with reference to Figure 4.

[0066] One or more tunnel junctions 310 and additional gain layers 311 can be placed between the active region 307 of the VCSEL diode 302 and the active region 314 of the RCPD 312. Depending on the polarity of the junction, the tunnel junction 310 can improve carrier injection / extraction from the VCSEL diode 302 to the RCPD 312 and help reduce the operating voltage of the photoelectron sensing device 300.

[0067] As an example, in one embodiment, the tunnel junction 310 of the VCSEL diode 302 can have a turn-on voltage (forward bias voltage to initiate lathing) of approximately 1.3V, and therefore the resulting turn-on voltage of the VCSEL diode 302 as a whole is approximately 2.6V. However, the current remains constant for a single tunnel junction, which in one embodiment is 0.5mA.

[0068] The tunnel junction 310 of the VCSEL diode 302 may be formed with both a highly doped n-type layer and a highly doped p-type layer. Examples of n-type dopants include, but are not limited to, silicon (Si), tellurium (Te), and selenium (Se). Examples of p-type dopants include, but are not limited to, carbon (C), zinc (Zn), and beryllium (Be). The highly doped concentration value is at least 10 18 / cm 3 The doping concentration may be as low as 10, and for some dopants, 10 20 / cm 3 While a single height is acceptable, other concentrations are also possible.

[0069] As shown in Figure 3, the current I flows through the VCSEL diode 302 between the common power supply contact 305a (shared with RCPD 312) and the power supply contact 305b of the VCSEL diode 302. LD 306 generates a forward bias that produces a primary radiation 340 directed towards the target object 350 through the substrate 308 and the on-chip lens 330. At the same time, a current I flows through the RCPD 312 between the common power supply contact 305a (shared with the VCSEL diode 302) and the power supply contact 315a of the RCPD 312. PD 316 generates a reverse bias via RCPD 312. To enable configurations for forward biasing the VCSEL diode 302 and RCPD 312, one or more controllers, such as the processor 1204 described below with reference to Figure 12, can be communicated to the photoelectron sensing device 300.

[0070] When the VCSEL diode 302 is forward-biased, the laser light of the primary emission 340 undergoes self-mixing interference within the laser cavity of the active region 307, upon reflection or backscattering. The RCPD 312 receives the self-mixed primary emission 340 and, when reverse-biased, detects the altered electrical characteristics of the primary emission 340. In some embodiments, one or more controllers may be configured to switch the bias polarity of the RCPD 312, as described with respect to Figure 6, to capture multiple detections of self-mixing interference in the time domain for time-multiplex sample readout.

[0071] Figure 4 shows a cross-sectional view of a lattice structure 320 configured to be placed on a set of multilayer semiconductor layers, such as, but not limited to, a substrate forming the exemplary photoelectron sensing device 300 of Figure 3 or the exemplary photoelectron sensing device 700 of Figure 7, which are described below. The lattice structure 320 may be a diffraction grating structure having a grating period larger than the wavelength of the primary emission. Alternatively, the lattice structure 320 may be a subwavelength grating structure having a grating period smaller than the wavelength of the primary emission. The lattice structure 320 is an optional feature that can have different structural modifications, such as, but not limited to, stabilizing the polarization of the emitted laser light, and may or may not be incorporated into the photoelectron sensing device depending on design requirements.

[0072] The lattice structure 320 is located on the upper surface of a pair of multilayer semiconductor layers, which may also include power supply contacts (e.g., power supply contact 315a in Figure 3) forming a ring or horseshoe shape around the lattice structure 320. The lattice structure 320 has a base layer 322 formed by alternating transverse arrangements of a high refractive index lattice material 323 (e.g., amorphous silicon, GaAs) and a low refractive index lattice material 324 (e.g., dielectric materials such as silicon oxide, aluminum oxide, silicon nitride) (e.g., using atomic layer deposition). An optional dielectric stack 326 of alternating DBR layers and dielectric layers (e.g., silicon oxide, aluminum oxide, silicon nitride) may be located on the base layer 322. A pair of DBR layers in the dielectric stack 326 assist in the reflection of laser light from a VCSEL diode (e.g., a VCSEL diode 302 in the photoelectron sensing device 300). The lattice structure 320 has a conductive layer 328 formed from a metal (e.g., gold, copper) placed on an optional dielectric stack 326. The top layer 328 electrically connects the power supply contacts of the VCSEL diode and / or RCPD, enhances the optical reflection of the emitted laser light, stabilizes the optional polarization of the emitted laser light, and also helps to bond the lattice structure 320 to other materials.

[0073] Figures 5A to 5D show schematic diagrams of the operating circuit in the exemplary photoelectron sensing device 300 of Figure 3. In Figure 5A, the VCSEL diode 302 may be forward-biased between the first bias node 512 and the common node 514, and the RCPD 312 may be reverse-biased between the common node 514 and the second bias node 516. For example, the first bias node 512 may be driven to a positive voltage such as 0.2V, the common node 514 may be driven to a positive voltage such as 3V, and the second bias node 516 may have a positive voltage such as 1.5V. The voltage of the second bias node 516 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different voltage levels may be used for the first bias node 512, the common node 514, and the second bias node 516, and generally, the voltage at the second bias node 516 is between the voltage at the first bias node 512 and the voltage at the common node 514. By forward-biasing the VCSEL diode 302, a cathode load current can be driven to cause the primary radiation 340 to radiate from it. By reverse-biasing the RCPD 312, the RCPD 312 may generate a photocurrent when it receives the primary radiation 340 whose characteristics have been altered due to self-mixing in the VCSEL diode 302. This photocurrent is detectable by a transimpedance amplifier (TIA) connected to the second bias node 516. In the configuration shown in Figure 5A, the common node 514 has n contacts and a tunnel junction exists between the VCSEL diode 302 and the RCPD 312.

[0074] In Figure 5B, the VCSEL diode 302 may be forward-biased between the first bias node 522 and the common node 524, and the RCPD 312 may be reverse-biased between the common node 524 and the second bias node 526. For example, the first bias node 522, the common node 524, and the second bias node 526 may generally be driven to progressively lower positive voltages such that the voltage at the common node 524 is between the voltage at the first bias node 522 and the voltage at the second bias node 526. The voltage at the second bias node 526 may depend on a transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 522, the common node 524, and the second bias node 526, but in the example shown in Figure 5B, the first bias node 522 may be driven to 4.3V, the common node 524 may be driven to 1.7V, and the second bias node 526 may have 0.2V. By forward biasing the VCSEL diode 302, an anode current can be driven to cause the primary radiation 340 to radiate from it. By reverse biasing the RCPD 312, the RCPD 312 may generate a photocurrent when it receives the primary radiation 340 whose characteristics have been altered due to self-mixing in the VCSEL diode 302. This photocurrent is detectable by a TIA connected to the second bias node 526. In the configuration shown in Figure 5A, the common node 524 has n contacts.

[0075] In Figure 5C, the VCSEL diode 302 may be forward-biased between the first bias node 532 and the common node 534, and the RCPD 312 may be reverse-biased between the common node 534 and the second bias node 536. For example, the first bias node 532 may be driven to a positive voltage such as 2.6V, the common node 534 may be held at 0V or ground (GND), and the second bias node 536 may have a positive voltage such as 1.5V. The voltage at the second bias node 536 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different voltage levels may be used for the first bias node 532, the common node 534, and the second bias node 536, and generally, the voltage at the second bias node 536 is between the voltage at the first bias node 532 and the voltage at the common node 534. By forward-biasing the VCSEL diode 302, an anode current can be driven to cause the primary radiation 340 to radiate from it. By reverse-biasing the RCPD 312, the RCPD 312 may generate a photocurrent when it receives the primary radiation 340 whose characteristics have been altered due to self-mixing in the VCSEL diode 302. This photocurrent can be detected by a TIA connected to a second bias node 536. In the configuration shown in Figure 5C, the common node 534 has n contacts, and a native reverse junction exists between the VCSEL diode 302 and the RCPD 312.

[0076] In Figure 5D, the VCSEL diode 302 may be forward-biased between the first bias node 542 and the common node 544, and the RCPD 312 may be reverse-biased between the second bias node 546 and the common node 544. For example, the first bias node 542, the common node 544, and the second bias node 546 may generally be driven to progressively higher positive voltages such that the voltage at the common node 544 is between the voltage at the first bias node 542 and the voltage at the second bias node 546. The voltage at the second bias node 546 may depend on a transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 542, the common node 544, and the second bias node 546. However, in the example shown in Figure 5D, the first bias node 542 may be held at 0V or ground (GND), the common node 544 may be driven to a positive voltage of 2.6V, and the second bias node 546 may have a positive voltage of 4.1V. By forward-biasing the VCSEL diode 302, a cathode load current can be driven to cause the primary radiation 340 to radiate from it. By reverse-biasing the RCPD 312, the RCPD 312 may generate a photocurrent when it receives the primary radiation 340 whose characteristics have been altered due to self-mixing in the VCSEL diode 302. This photocurrent is detectable by a TIA connected to the second bias node 546. In the configuration shown in Figure 5A, the common node 544 has a p-contact.

[0077] Figure 6 shows a schematic diagram of the operating circuit in the exemplary photoelectron sensing device 300 of Figure 3, where the bias polarity of the RCPD 312 is switched in the time domain. In Figure 6, the VCSEL diode 302 may be forward-biased between the first bias node 612 and the common node 614, and the RCPD 312 may be reverse-biased or forward-biased between the common node 614 and the second bias node 616. In different embodiments, different voltage levels may be used for the first bias node 612, the common node 614, and the second bias node 616. By forward-biasing the VCSEL diode 302, a cathode load current can be driven, thereby causing the primary radiation 340 to radiate from there, which is received by the RCPD 312, and its characteristics are changed by self-mixing within the VCSEL diode 302, subsequently generating a photocurrent. This photocurrent is detectable by a TIA connected to the second bias node 616. The bias polarity of the RCPD 312 may be switched in the time domain, which enables time-multiplexed sample readout of the photocurrent.

[0078] Figure 7 shows a cross-sectional view of an exemplary photoelectronic sensing device 700 having a second exemplary structure 200 of a back-emitting VCSEL diode integrated with an RCPD (shown in Figure 2). In particular, the back-emitting VCSEL diode 702 is integrated with an RCPD 712 positioned along the path of the primary emission 740 of the laser light generated from the VCSEL diode 702 under forward bias. The RCPD 712 receives the modified primary emission from the VCSEL diode 702 after the primary emission 740 has undergone self-mixing interference when it receives reflections or backscatters within it.

[0079] The photoelectron sensing device 700 is first fabricated by depositing a pair of mirror layers 710 on the surface 708f of the substrate 708. In some embodiments, the pair of mirror layers 710 may be DBR layers as described above. The power supply contact 715a may be located on the upper surface of the pair of mirror layers 710, or it may form a ring or horseshoe-shaped connection around the RCPD 712 deposited on the pair of mirror layers 710. The on-chip lens 730 is located on the rear surface 708r of the substrate 708 and is configured to collimate the laser light emitted by the VCSEL diode 702 and reflect back a portion of the primary radiation toward the first active region in the VCSEL diode 702 and the RCPD 712.

[0080] The RCPD 712 is epitaxially deposited on a pair of mirror layers 710. In some embodiments, the RCPD 712 may include an active region 714 and a power supply contact 715b located on its upper surface. The active region 714 may include one or more gain layers (e.g., an InGaAs layer, an AlGaAs layer) to improve the absorption efficiency of the altered primary radiation 740 after it has undergone self-mixing interference within the active region 707 of the VCSEL diode 302. The power supply contact 715b forms a ring or horseshoe-shaped connection on the upper side of the RCPD 312.

[0081] The VCSEL diode 702 is formed on the RCPD 712 by an epitaxial deposition technique or the like. The VCSEL diode 702 may include an emitting-side (or "upper") DBR layer 703a that functions as a first (or "emitting-side") mirror of the laser structure. The emitting-side DBR layer 703a may include a pair of alternating materials having different refractive indices. One or more materials in the emitting-side DBR layer 703a may be doped to be p-type and thus form part of the anode portion of the pn diode junction of the VCSEL diode 702. An exemplary pair of materials that may be used to form the emitting-side DBR layer 703a is AlGaAs and GaAs.

[0082] The VCSEL diode 702 can also include a base - side DBR layer 703b that functions as the second (or "base - side" or "bottom - side") mirror of the laser. The base - side DBR layer 703b can also include a set of Bragg pairs of alternating materials having different refractive indices. One or more materials within the base - side DBR layer 703b may be doped to be n - type, and thus form part of the cathode portion of the p - n diode structure. An exemplary pair of materials that can be used to form the base - side DBR layer 703b are AlAs and GaAs.

[0083] In some embodiments, the DBR layers 703a and 703b can be formed of semiconductor epitaxy, and for (0 < x ≤ 1), semiconductor GaAs, Al x Ga 1-x As, or any other semiconductor material. In other embodiments, the DBR layers 703a and 703b can be formed of dielectric materials. Examples of such dielectrics include, but are not limited to, amorphous silicon (a - Si), silicon oxide (SiO2), SiO 2 / Nb2O5, and SiO2 / Ta2O5. In yet other embodiments, the DBR layers 703a and 703b can be formed as a hybrid of semiconductor materials and dielectric materials.

[0084] The VCSEL diode 702 can include an active region 707 that functions partially as a resonant cavity. In a laser diode such as the VCSEL diode 702, the active region 707 can include one or more quantum wells. In some embodiments as shown in FIG. 7, the active region 707 of the VCSEL diode 702 may be adjacent to an oxide layer 709 having an aperture through which the primary emission 740 escapes. In some embodiments as shown in FIG. 7, the active region 707 further includes one or more gain - layer 704 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the VCSEL diode 702 to improve the absorption efficiency of the primary emission 740.

[0085] The VCSEL diode 702 can be formed by epitaxial growth of each of the layers, including the radiating DBR layer 703a and the base DBR layer 703b, the active region 707, and the oxide layer 709, and optionally other layers. These various layers can be formed by epitaxial growth on the RCPD 712. The power supply contact 705a can be formed on the radiating and base layers of the VCSEL diode 702. The lattice structure 320 can be arranged on the VCSEL diode 702, as will be further described with reference to Figure 4.

[0086] One or more tunnel junctions (such as the tunnel junction 310 described in Figure 3) and an additional gain layer (such as the tunnel junction 311 described in Figure 3) can be placed between the active region 707 of the VCSEL diode 702 and the active region 714 of the RCPD 712. Depending on the polarity of the junction, such tunnel junctions can improve carrier injection / extraction from the VCSEL diode 702 to the RCPD 712 and help reduce the operating voltage of the photoelectron sensing device 700.

[0087] As shown in Figure 7, the current I flows through the VCSEL diode 702 between the power supply contact 705a of the VCSEL diode 702 and the common power supply contact 715b (shared with RCPD 712). LD 706 generates a forward bias that produces a primary radiation 740 directed towards the target object 750 through the substrate 708 and the on-chip lens 730. At the same time, a current I flows through the RCPD 312 between the common power supply contact 715b (shared with the VCSEL diode 702) and the power supply contact 715a of the RCPD 712. PD 716 generates a reverse bias through RCPD 712. To enable configurations for forward biasing the VCSEL diode 702 and RCPD 712, one or more controllers, such as the processor 1204 described below with reference to Figure 12, can be communicatively connected to the photoelectron sensing device 700.

[0088] When the VCSEL diode 702 is forward-biased, the laser light of the primary emission 740 undergoes self-mixing interference within the laser cavity of the active region 707, upon reflection or backscattering. The RCPD 712 receives the self-mixed primary emission 740 and, upon reverse biasing, detects the altered electrical characteristics of the primary emission 740.

[0089] Figures 8A to 8D show schematic diagrams of the operating circuit in the exemplary photoelectron sensing device 700 of Figure 7. In Figure 8A, the VCSEL diode 702 may be forward-biased between the first bias node 812 and the common node 814, and the RCPD 712 may be reverse-biased between the common node 814 and the second bias node 816. For example, the first bias node 812 may be driven to a positive voltage such as 2.6V, the common node 814 may be held at 0V or ground (GND), and the second bias node 816 may have a positive voltage such as 1.5V. The voltage of the second bias node 816 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different voltage levels may be used for the first bias node 812, the common node 814, and the second bias node 816. By forward-biasing the VCSEL diode 702, an anode drive current can be provided that causes the primary radiation 740 to radiate from there. By reverse-biasing RCPD 712, a photocurrent can be generated when RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 816. In the configuration shown in Figure 8A, the common node 814 has n-contacts, and a native reverse junction is formed between the VCSEL diode 702 and RCPD 712.

[0090] In Figure 8B, the VCSEL diode 702 may be forward-biased between the first bias node 822 and the common node 824, and the RCPD 712 may be reverse-biased between the common node 824 and the second bias node 826. For example, the first bias node 822, the common node 824, and the second bias node 826 may be driven to progressively lower positive voltages. The voltage of the second bias node 826 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 822, the common node 824, and the second bias node 826, but in the example shown in Figure 8B, the first bias node 822 may be driven to 4.3V, the common node 824 may be driven to 1.7V, and the second bias node 826 may have 0.2V. By forward-biasing the VCSEL diode 702, an anode current can be driven, causing the primary radiation 740 to radiate from it. By reverse-biasing the RCPD 712, a photocurrent can be generated when the RCPD 712 receives the primary radiation 740, whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent is detectable by a TIA connected to a second bias node 826. In the configuration shown in Figure 8A, the common node 824 has n contacts.

[0091] In Figure 8C, the VCSEL diode 702 may be forward-biased between the first bias node 832 and the common node 834, and the RCPD 712 may be reverse-biased between the common node 834 and the second bias node 836. For example, the first bias node 832 may be held at 0V or ground (GND), the common node 834 may be driven to a positive voltage of 2.8V, and the second bias node 836 may have a positive voltage such as 1.3V. The voltage of the second bias node 836 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different voltage levels may be used for the first bias node 832, the common node 834, and the second bias node 836. By forward-biasing the VCSEL diode 702, a cathode load current can be driven to cause the primary radiation 740 to radiate from it. By reverse-biasing RCPD 712, a photocurrent can be generated when RCPD 712 receives primary radiation 740 whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 836. In the configuration shown in Figure 8C, the common node 834 has n contacts, and a tunnel junction exists between the VCSEL diode 702 and RCPD 712.

[0092] In Figure 8D, the VCSEL diode 702 may be forward-biased between the first bias node 842 and the common node 844, and the RCPD 712 may be reverse-biased between the second bias node 846 and the common node 844. For example, the first bias node 842, the common node 844, and the second bias node 846 may be driven to progressively higher positive voltages. The voltage of the second bias node 846 may depend on the transimpedance amplifier (TIA) or other readout circuit connected to it. In different embodiments, different sets of positive voltage levels may be used for the first bias node 842, the common node 844, and the second bias node 846, but in the example shown in Figure 8D, the first bias node 842 may be held at 0V or ground (GND), the common node 844 may be driven to 2.6V, and the second bias node 846 may have 4.1V. By forward-biasing the VCSEL diode 702, a cathode load current can be driven to cause the primary radiation 740 to radiate from it. By reverse-biasing the RCPD 712, a photocurrent can be generated when the RCPD 712 receives the primary radiation 740, whose characteristics have been altered due to self-mixing in the VCSEL diode 702. This photocurrent can be detected by a TIA connected to a second bias node 846. In the configuration shown in Figure 8A, the common node 844 has a p-contact.

[0093] Figures 9A and 9B show cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectron sensing device 900 having a back-emitting VCSEL diode with a multi-junction structure (MJ-VCSEL) and an extended resonant cavity on the radiating side, as described below. The extended resonant cavity extends from the VCSEL diode to an on-chip lens (OCL) 930 formed on the rear surface 908r of the substrate 908, and includes the substrate 908. In particular, Figure 9A shows a back-emitting MJ-VCSEL diode 902 integrated with an RCPD 912 positioned away from the path of the primary emission 940 of laser light from the MJ-VCSEL diode 902 under forward bias. The RCPD 912 receives the modified primary emission 940 from the MJ-VCSEL diode 902 after the primary emission 940 has undergone self-mixing interference when it receives reflections or backscatters within it.

[0094] The photoelectron sensing device 900 is fabricated by first forming a substrate 908 (e.g., a low-loss semiconductor or dielectric material) having an expanded cavity, depositing a set of multilayer semiconductor layers on the surface 908f of the substrate 908 to form an MJ-VCSEL diode 902 having a multijunction structure 901, and then forming an RCPD 912 on the VCSEL diode 902. As described above, the expanded resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-distance sensing. The on-chip lens 930 is positioned on the rear surface 908r of the substrate 908 and is configured to collimate the laser light emitted by the VCSEL diode 902 and collect the return laser light that returns from the target object towards the VCSEL diode 902 and the first active region in the RCPD 912. A reflective coating 935 made of a dielectric material may be positioned on the on-chip lens 930.

[0095] Similar to the embodiments described with respect to Figure 3, the MJ-VCSEL diode 902 may include an radiating (or "upper") DBR layer 903a comprising a pair of alternating materials having different refractive indices (e.g., AlGaAs, GaAs). The MJ-VCSEL diode 902 may also include a base-side DBR layer 903b comprising a pair of Bragg pairs of alternating materials having different refractive indices (e.g., AlAs, GaAs). One or more of the materials in the radiating DBR layer 903a and the base-side DBR layer 903b may be p-type and n-type doped, respectively, thus forming a portion of the anode and cathode of the pn diode structure, respectively.

[0096] Between the DBR layers 903a and 903b, the MJ-VCSEL diode 902 may have multiple active regions 907a, 907b, 907c (e.g., multiple pairs of barrier layers alternating with the quantum well layer) that generate laser light when stimulated by a forward bias voltage. Highly doped tunnel junctions 910a, 910b, 910c (similar to the tunnel junction 310 described above with respect to Figure 3) can be scattered in the multiple active regions 907a, 907b, 907c to form a vertically stacked multi-junction structure 901 within the MJ-VCSEL diode 902. One or more gain layers 911a, 911b, 911c (similar to the gain layer 311 described above with respect to Figure 3) may be coupled to the tunnel junctions 910a, 910b, 910c in the multi-junction structure 901, respectively. In the embodiment shown in Figure 9A, there are three active regions 907a to 907c, each containing three tunnel junctions 910a, 910b, and 910c, which are each coupled to one of the three gain layers 911a, 911b, and 911c. However, in other embodiments, the MJ-VCSEL diode 902 may have two or more layers of each type that form a vertical stack between the DBR layers 903a and 903b.

[0097] Generally, in MJ-VCSEL diodes having different numbers of active regions, there is a tunnel junction between each successive pair of active regions. As shown in FIG. 9A, in MJ-VCSEL diode 902, there is a first tunnel junction 910a between active regions 907a and 907b, and a second tunnel junction 910b between active regions 907b and 907c. Optionally, MJ-VCSEL diode 902 can also include one or more tunnel junctions at locations other than between successive pairs of active regions 907a-907c, such as tunnel junction 910c between active region 907c and RCPD 912. The tunnel junctions 910a-910c of MJ-VCSEL diode 902 can be of the same type or different types. Semiconductor materials that can be used for the tunnel junction layer include GaAs (0 < x ≤ 1, 0 < y < 1), Al x Ga 1-x As, In x Ga 1-x As, In x Ga 1-x P, GaAs 1-x N x 、In x Ga 1-x As y P 1-y 、and others known to those skilled in the art. Depending on the polarity of the junction, the tunnel junctions 910a-910c help improve carrier injection / extraction from MJ-VCSEL diode 902 to RCPD 912 and reduce the operating voltage of optoelectronic sensing device 900.

[0098] Each of the active regions 907a-c includes a plurality of barrier layers and quantum well layers. Materials that can be used for the barrier layers of the active regions 907a-c include Al x Ga 1-x As (0 < x ≤ 1), GaAs 1-x P x (0 < x ≤ 1), and others known to those skilled in the art. Materials that can be used for the quantum wells of the active regions 907a-c include In x Ga 1-x As (0 < x ≤ 1), In x Ga 1-x As y N 1-y, (0 < x ≤ 1, 0 < y ≤ 1), In x Ga 1-x As 1-y-z N y Sb z (0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1), and others known to those skilled in the art are included.

[0099] The MJ-VCSEL diode 902 includes a radiation side (or "upper") oxide layer 909a disposed adjacent to the uppermost active region 907a or on the upper surface of the MJ-VCSEL diode 902, and a base side (or "bottom") oxide layer 909c disposed adjacent to the lowermost active region 907c or on the bottom surface of the MJ-VCSEL diode 902. The oxide layer 909c includes an opening (or openings) through which the primary radiation 940 escapes. The MJ-VCSEL diode 902 can also include an additional oxide layer 909b adjacent to the active region 907b. Each of the oxide layers 909a and 909b includes an opening (or openings) that allows the primary radiation 940 to pass between the active regions 907a - 907c. Other embodiments of the MJ-VCSEL diode may not have an oxide layer between consecutive active regions, or may have two or more. The openings in the oxide layers 909a - c allow the laser light generated within the active regions 907a - 907c to pass through each other and can enhance the generation of the primary radiation 940 of the laser light emitted through the optoelectronic sensing device 900.

[0100] In some embodiments as shown in FIG. 9A, each of the active regions 907a - 907c further includes one or more gain layer segments 904 (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the MJ-VCSEL diode 902 to improve the efficiency of the reabsorption of the primary radiation 940 into the MJ-VCSEL diode 902.

[0101] The MJ-VCSEL diode 902 can be formed by epitaxially growing the radiating DBR layer 903a, the multijunction structure 901, and the base-side DBR layer 903b on a substrate 908. Subsequently, the RCPD 912 is also formed on the MJ-VCSEL diode 902. In some embodiments, the RCPD 912 may include an active region 914, which may include one or more gain layers (e.g., an InGaAs layer, an AlGaAs layer) to improve the absorption efficiency of the altered primary radiation 940 after it has undergone self-mixing interference within the active regions 907a-907c of the VCSEL diode 902. The lattice structure 320 may be arranged perpendicularly on a set of multilayer semiconductor layers forming the RCPD 912, as will be further described with reference to Figure 4.

[0102] The MJ-VCSEL diode 902 may have a common power supply contact 905a (shared with the RCPD 912) located on or near the base-side DBR layer 903b, a first power supply contact 905b located on or near the radiating-side DBR layer 903a, and a second power supply contact 915a located on the RCPD 912. The common power supply contact 905a, the first power supply contact 905b, and the second power supply contact 915a may form a ring or horseshoe-shaped connection around the base-side DBR layer 903b, the radiating-side DBR layer 903a, and the RCPD 912, respectively.

[0103] When a bias voltage is applied, the laser diode current I LD Current 906 can be passed through the VCSEL diode 902 between the common power supply contact 905a and the first power supply contact 905b to generate primary radiation 940. This generates primary radiation 940 directed towards the target object 950 through the substrate 908 and the on-chip lens 930. At the same time, current I flows through the RCPD 912 between the common power supply contact 905a and the second power supply contact 915a of the RCPD 912. PD916 generates a reverse bias through RCPD 912. To enable a configuration that forward-biases VCSEL diode 902 and reverse-biases RCPD 912, one or more controllers, such as processor 1204 as described below with respect to Figure 12, can be communicatively connected to the photoelectron sensing device 900.

[0104] When the VCSEL diode 902 is forward-biased, the laser light of the primary emission 940 undergoes self-mixing interference within the laser cavity of the active region 907a-c after being reflected or backscattered. The RCPD 912 receives the self-mixed primary emission 940 and, when reverse-biased, detects the altered electrical characteristics of the primary emission 940.

[0105] The MJ-VCSEL diode 902 can emit laser light with different characteristics than those emitted by a single-junction VCSEL (SJ-VCSEL) diode 302 (shown in Figure 3) operating at a similar current level. The MJ-VCSEL diode 902 operates at an increased voltage level (compared to the SJ-VCSEL diode 302 operating at a similar current level), which can provide several factors, such as an increase in output power gain. It can also increase the center frequency of the emitted laser light, thereby improving the signal-to-noise ratio (SNR) as 1 / f noise is reduced. The increased SNR and higher operating frequency also enable improved spatial resolution of the target by the photoelectronic sensing device 900 having the MJ-VCSEL diode 902, due to the increased efficiency and adjustable range for wavelength modulation of the emitted laser light by the MJ-VCSEL diode 902, which in turn enables better measurement of electrical parameters related to the self-mixing interference of the emitted laser light. Thus, the multi-junction structure 901 improves the performance of the photoelectronic sensing device 900 through faster signal transmission, wider sampling, and reduced complexity.

[0106] In Figure 9B, the VCSEL diode 902 may be forward-biased between the first bias node 992 and the common node 994, and the RCPD 912 may be reverse-biased between the common node 994 and the second bias node 996. For example, the first bias node 992 may be driven to a positive voltage such as 0.2V, the common node 994 may be driven to a positive voltage such as 6V, and the second bias node 996 may be driven to a positive voltage such as 4.5V. In different embodiments, different voltage levels may be used for the first bias node 992, the common node 994, and the second bias node 996. Forward-biasing the VCSEL diode 902 can drive a cathode load current that causes primary radiation 940a to 940c to radiate from the multi-junction structure 901 having active regions 907a to 907c where tunnel junctions 910a to 910c are scattered. By reverse-biasing RCPD 912, a photocurrent can be generated when RCPD 912 receives primary radiation 940a-940c whose characteristics have been altered due to self-mixing in the VCSEL diode 902. This photocurrent can be detected by a TIA connected to a second bias node 996 or by another readout circuit. As described above, the multi-junction structure 901 in Figure 9A increases the tunability of thermal resistance and wavelength modulation for better measurement of self-mixing interference.

[0107] Figures 10A and 10B show cross-sectional and corresponding schematic diagrams of the operating circuit of a first exemplary photoelectron sensing device 1000, which has multiple sets of back-emitting VCSEL diodes (similar to VCSEL diode 302 described in Figure 3) integrated with an RCPD (similar to RCPD 312 described in Figure 3) positioned away from the primary radiation path of the VCSEL diodes. The photoelectron sensing device 1000 has a first arrangement of electrical connections between the multiple sets, as described below.

[0108] As shown in Figure 10A, the photoelectron sensing device 1000 forms an injection layer 1009 on the surface 1008f of the substrate 1008, and then the first set of mesa 10101, 10102, 10103 and the second set of mesa 1010a , 1010 b , 1010 c To form the mesas, a set of multilayer semiconductor layers is fabricated by depositing them on the injection layer 1009 (for example, by epitaxial deposition technique). Three sets of mesas are shown in the embodiment of Figure 10A, but each set of mesas in different embodiments may include more or fewer mesas forming each number of emitters. Each of the mesas 10101, 10102, and 10103 includes individual back-emitting VCSEL diodes 10021, 10022, and 10023 integrated with individual RCPDs 10121, 10122, and 10123 placed on top of it. Individual lattice structures 10201, 10202, and 10203 are placed on top of each of the individual RCPDs 10121, 10122, and 10123. Each of the mesas 10101, 10102, and 10103 forms separate emitters #1, #2, and #3, respectively, thereby emitting separate primary emissions 10401, 10402, and 10403 through separate back-emitting VCSEL diodes 10021, 10022, and 10023, respectively, via on-chip lenses 10301, 10302, and 10303 located on the rear surface 1008r of the substrate 1008.

[0109] Each of the individual VCSEL diodes 10021, 10022, and 10023 may include individual active regions 10071, 10072, and 10073 (similar to the active region 307 described in relation to Figure 3) (not shown), which may contain one or more quantum wells, and may be adjacent to their respective oxide layers (not shown) having openings from which the individual primary radiations 10401, 10402, and 10403 escape. The individual active regions 10071, 10072, and 10073 may also include their respective gain stage layers 10041, 10042, and 10043 (e.g., InGaAs layer, AlGaAs layer) (not shown) to improve the absorption efficiency of the individual primary radiations 10401, 10402, and 10403. Each individual RCPD 10121, 10122, 10123 may include its respective active regions 10141, 10142, 10143, which may also include one or more gain layers (e.g., InGaAs layer, AlGaAs layer) to improve the absorption efficiency of the individual altered primary radiations 10401, 10402, 10403 after self-mixing interference has occurred in the individual active regions 10071, 10072, 10073 of each VCSEL diode 10021, 10022, 10023. One or more tunnel junctions and gain layers may be placed between the individual active regions 10071, 10072, 10073 of each VCSEL diode 10021, 10022, 10023 and the individual active regions 10141, 10142, 10143 of RCPD 10121, 10122, 10123.

[0110] When the individual VCSEL diodes 10021, 10022, and 10023 are forward-biased, the laser light from the individual primary emitters 10401, 10402, and 10403 undergoes self-mixing interference within the individual active regions 10071, 10072, and 10073 upon reflection or backscattering. One of the corresponding RCPDs 10121, 10122, and 10123 receives the individual self-mixing primary emitters 10401, 10402, and 10403 and, when reverse-biased, detects the altered electrical properties of the individual self-mixing primary emitters 10401, 10402, and 10403.

[0111] In some embodiments, the first set of mesas 10101, 10102, 10103 and the second set of mesas 1010 a , 1010 b , 1010 c These may be formed by epitaxially growing a common set of semiconductor layers to form trenches 1070, 1080 to define the respective mesas, and then electrically connecting a selected number of mesas to perform different functions or provide different routing structures. In the embodiment shown in Figure 10A, the second set of mesas 1010 a , 1010 b , 1010 c Each of these is adjacent to one of the mesas 10101, 10102, and 10103 of the first group and separated by a connecting trench 1070 (formed, for example, by etching through a set of multilayer semiconductor layers). a The second group of adjacent mesa 10102, 10100 is separated by isolation trench 1080 (also formed by etching through a pair of multilayer semiconductor layers) which penetrates the injection layer 1009 and provides electrical isolation between the respective active regions 10071, 10072, 10073 of the respective VCSEL diodes 10021, 10022, 10023. b It can be separated from. The conductive layer 1060 (e.g., gold, copper) is placed on individual lattice structures 10201, 10202, 10203 on each RCPD 10121, 10122, 10123 and the second set of mesa 1010 a , 1010 b , 1010 c Each of them is routed over, providing electrical connectivity across a set of mesas.

[0112] Each of the mesas 10101, 10102, and 10103 includes a common power supply contact 10051, 10052, and 10053 shared between the corresponding VCSEL diodes 10021, 10022, and 10023 and the individual RCPDs 10121, 10122, and 10123 positioned on top of them. As shown in Figure 10A, the bias voltage applied through the individual common power supply contacts 10051, 10052, and 10053 provides a forward bias (current I) in each VCSEL diode 10021, 10022, and 10023. LD 1006 1、 1006 2、 10063) can be generated to produce individual primary radiations 10401, 10402, and 10403 directed towards the target object 1050 through the substrate 1008 and their respective on-chip lenses 10301, 10302, and 10303. At the same time, the reverse bias (current I) in each of the RCPDs 10121, 10122, and 10123 can be generated. PD 10161, 1016 2、 10163) helps to detect the altered characteristics of the respective primary emissions 10401, 10402, and 10403 due to self-mixing interference in the respective active regions 10071, 10072, and 10073 of the individual VCSEL diodes 10021, 10022, and 10023. One or more controllers, such as the processor 1204 described below with respect to Figure 12, can be communicatively connected to the photoelectron sensing device 1000 to enable configurations for forward biasing the individual VCSEL diodes 10021, 10022, and 10023 and reverse biasing the individual RCPDs 10121, 10122, and 10123.

[0113] The specific arrangement of electrical connections in the photoelectron sensing device 1000 having a conductive layer 1160 allows for the individual addressability of each emitter, which is formed by one of each of the mesas 10101, 10102, and 10103. As a result, any selection of one or more emitters, emitter #1, emitter #2, and emitter #3, can be used as a sensor for detecting the distance and motion of a target object 1050 using self-mixing interference captured by individual back-emitting VCSEL diodes 10021, 10022, and 10023 integrated with individual RCPDs 10121, 10122, and 10123 placed on it.

[0114] As shown in Figure 10B, each of the back-emitting VCSEL diodes 10021, 10022, and 10023 may be forward-biased between the first bias node 1092 and the common node 1094 (via common power supply contacts 10051, 10052, and 10053), and the individual RCPDs 10121, 10122, and 10123 may be reverse-biased between the common node 1094 and the second bias node 1096. The first bias node 1092 and the common node 1094 may have different positive voltages so that the individual VCSEL diodes 10021, 10022, and 10023 are driven by the cathode load current that causes the individual primary radiators 10401, 10402, and 10403 to radiate from there. The second bias node 1096 and the common node 1094 may also have different positive voltages, thereby reverse-biasing the individual RCPDs 10121, 10122, and 10123 such that a photocurrent is generated when the individual RCPDs 10121, 10122, and 10123 receive individual primary radiation 10401, 10402, and 10403 whose characteristics have been altered due to self-mixing in the VCSEL diodes 10021, 10022, and 10023. This photocurrent is detectable by a TIA connected to the second bias node 1096. As described above, this arrangement allows for addressability of the individual emitters formed by the individual back-emitting VCSEL diodes 10021, 10022, and 10023 integrated with the individual RCPDs 10121, 10122, and 10123 placed on top of it.

[0115] Figures 11A and 11B show cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectron sensing device 1100, which has multiple sets of back-emitting VCSEL diodes (similar to VCSEL diode 302 described in Figure 3) integrated with an RCPD (similar to RCPD 312 described in Figure 3) positioned away from the primary radiation path of the VCSEL diodes. The photoelectron sensing device 1100 has a first arrangement of electrical connections between the multiple sets, as described below.

[0116] As shown in Figure 11A, the photoelectron sensing device 1100 forms an injection layer 1109 on the surface 1108f of the substrate 1108, and then the first set of mesa 11101, 11102, 11103 and the second set of mesa 1110 a , 1110 b , 1110 c To form the mesas, a set of multilayer semiconductor layers is fabricated by depositing them on the injection layer 1109 (for example, by epitaxial deposition technique). Three sets of mesas are shown in the embodiment of Figure 11A, but each set of mesas in different embodiments may include more or fewer mesas forming each number of emitters. Each of the mesas 11101, 11102, and 11103 includes individual back-emitting VCSEL diodes 11021, 11022, and 11023 integrated with individual RCPDs 11121, 11122, and 11123 placed on top of it. Individual lattice structures 11201, 11202, and 11203 are placed on top of each of the individual RCPDs 11121, 11122, and 11123. Each of the mesas 11101, 11102, and 11103 forms separate emitters #1, #2, and #3, respectively, thereby emitting separate primary emissions 11401, 11402, and 11403 through separate back-emitting VCSEL diodes 11021, 11022, and 11023, respectively, via on-chip lenses 11301, 11302, and 11303 located on the rear surface 1108r of the substrate 1108.

[0117] Each of the VCSEL diodes 11021, 11022, and 11023 may contain individual active regions 11071, 11072, and 11073 (similar to the active region 307 described in relation to Figure 3) (not shown), which may contain one or more quantum wells, and may be adjacent to individual oxide layers (not shown) having openings from which individual primary radiations 11401, 11402, and 11403 escape. The individual active regions 11071, 11072, and 11073 may also contain respective gain stage layers 11041, 11042, and 11043 (e.g., InGaAs layers, AlGaAs layers) (not shown) to improve the absorption efficiency of the individual primary radiations 11401, 11402, and 11403. Individual RCPDs 11121, 11122, and 11123 may include their respective active regions 11141, 11142, and 11143, which may also include one or more gain layers (e.g., InGaAs layers, AlGaAs layers) to improve the absorption efficiency of the individually altered primary radiation 11401, 11402, and 11403 after self-mixing interference has occurred in the individual active regions 11071, 11072, and 11073 of each VCSEL diode 11021, 11022, and 11023. One or more tunnel junctions and gain layers may be placed between the individual active regions 11071, 11072, and 11073 of each VCSEL diode 11021, 11022, and 11023 and the individual active regions 11141, 11142, and 11143 of RCPDs 11121, 11122, and 11123.

[0118] When the individual VCSEL diodes 11021, 11022, and 11023 are forward-biased, the laser light from the individual primary emitters 11401, 11402, and 11403 undergoes self-mixing interference within the individual active regions 11071, 11072, and 11073, upon reflection or backscattering. One of the corresponding RCPDs 11121, 11122, and 11123 receives the individual self-mixing primary emitters 11401, 11402, and 11403 and, when reverse-biased, detects the altered electrical properties of the individual self-mixing primary emitters 11401, 11402, and 11403.

[0119] In some embodiments, the first set of mesas 11101, 11102, 11103 and the second set of mesas 1110 a , 1110 b , 1110 c These may be formed by epitaxially growing a common set of semiconductor layers to form trenches 1170, 1180 to define each mesa, and then electrically connecting a selected number of mesa to perform different functions or provide different routing structures. In the embodiment shown in Figure 10A, the second set of mesa 1110 a , 1110 b , 1110 c Each of these is adjacent to one of the mesas 11101, 11102, and 11103 of the first group and separated by a photodetector trench 1170 (formed, for example, by etching through a set of multilayer semiconductor layers) which provides electrical connections to the trailing end of one of the RCPDs 11121, 11122, and 11123. a The oxide trenches 1180 (which are also formed by etching through a set of multilayer semiconductor layers) provide electrical insulation between the respective active regions 11071, 11072, and 11073 of the respective VCSEL diodes 11021, 11022, and 11023, respectively, and adjacent mesas 11102, b The conductive layer 1160 (e.g., gold, copper) is placed on the individual lattice structures 11201, 11202, 11203 on each of the RCPDs 11121, 11122, 11123, and on the second set of mesa 1110 a , 1110 b , 1110 c They are positioned on top of each of them, providing electrical connections across a set of mesas.

[0120] The photoelectron sensing device 1100 is located on the injection layer 1109 and includes a common power supply contact 1105 shared by the respective back-emitting VCSEL diodes 11021, 11022, and 11023, and the respective RCPDs 11121, 11122, and 11123 located on top of them. As shown in Figure 11A, the bias voltage applied through the common power supply contact 1105 forward-biassed (current I) each of the respective VCSEL diodes 11303, 11022, and 11023 to generate the respective primary emissions 11401, 11402, and 11403 directed towards the target object 1150 through the substrate 1108 and the respective on-chip lenses 11301, 11302, and 11021. LD It is possible to generate 11061, 11062, and 11063. At the same time, a reverse bias (current I) can be generated in each of the RCPDs 11121, 11122, and 11123. PD The 11161, 11162, and 11163) help detect the altered characteristics of the respective primary radiations 11401, 11402, and 11403 resulting from self-mixing interference in the respective active regions 11071, 11072, and 11073 of the individual VCSEL diodes 11021, 11022, and 11023. To enable a configuration in which the individual VCSEL diodes 11021, 11022, and 11023 are forward-biased and the individual RCPDs 11121, 11122, and 11123 are reverse-biased, one or more controllers, such as the processor 1204 described below with reference to Figure 12, can be communicatively connected to the photoelectron sensing device 1100.

[0121] The specific arrangement of electrical connections within the photoelectron sensing device 1100 having a conductive layer 1160 allows for the individual addressability of each emitter, each formed by one of the mesas 11101, 11102, and 11103. As a result, any selection of one or more emitters, emitter #1, emitter #2, and emitter #3, can be used as a sensor for detecting the distance and motion of a target object 1150 using self-mixing interference captured by individual back-emitting VCSEL diodes 11021, 11022, and 11023 integrated with individual RCPDs 11121, 11122, and 11123 placed on it.

[0122] As shown in Figure 11B, each of the back-emitting VCSEL diodes 11021, 11022, and 11023 may be forward-biased between the first bias node 1192 and the common node 1194 (via the common power supply contact 1105), while the individual RCPDs 11121, 11122, and 11123 may be reverse-biased between the first bias node 1192 and the second bias node 1196. The first bias node 1192 and the common node 1194 may have different positive voltages so that the individual VCSEL diodes 11021, 11022, and 11023 are driven by the cathode load current that causes the individual primary radiators 11401, 11402, and 11403 to radiate from there. The first bias node 1192 and the second bias node 1196 may also have different positive voltages, thereby reverse-biasing the individual RCPDs 11121, 11122, and 11123 such that a photocurrent is generated when the individual RCPDs 11121, 11122, and 11123 receive individual primary radiation 11401, 11402, and 11403 whose characteristics have been altered due to self-mixing in the VCSEL diodes 11021, 11022, and 11023. This photocurrent is detectable by a TIA connected to the second bias node 1196. As described above, this arrangement allows for addressability of the individual emitters formed by the individual back-emitting VCSEL diodes 11021, 11022, and 11023 integrated with the individual RCPDs 11121, 11122, and 11123 placed thereon.

[0123] Figures 12A and 12B show cross-sectional and corresponding schematic diagrams of the operating circuit of a second exemplary photoelectron sensing device 1200, which has an extended resonant cavity on the radiating side of a back-emitting MJ-VCSEL diode and is integrated with an RCPD, as described herein. The second example of the photoelectron sensing device 1200 shown in and described with reference to Figures 12A and 12B may have improved performance. In particular, the photoelectron sensing device 1200 may have a relatively more stable polarization than other photoelectron sensing devices and may be more stable in optical modes. In some cases, the photoelectron sensing device 1200 may have a relatively higher signal intensity for the RCPD output signal compared to other photoelectron sensing devices.

[0124] The extended resonant cavity of the photoelectron sensing device 1200 extends from the RCPD to the OCL 1230 formed on the rear surface 1208r of the substrate 1208, encompassing the substrate 1208. In particular, Figure 12A shows a back-emitting MJ-VCSEL diode 1202 integrated with an RCPD 1212 positioned in the path of the primary emission 1240 of laser light from the MJ-VCSEL diode 1202 under forward bias. The RCPD 1212 receives the modified primary emission 1240 from the MJ-VCSEL diode 1202 after the primary emission 1240 has undergone self-mixing interference upon reception of reflection or backscatter within it.

[0125] The photoelectron sensing device 1200 is fabricated by first forming a substrate 1208 (e.g., a low-loss semiconductor or dielectric material) having an expanded cavity, forming an RCPD 1212 on the surface 1208f of the substrate, and then depositing a set of multilayer semiconductor layers on the RCPD 1212 to form an MJ-VCSEL diode 1202 having a multijunction structure. As described above, the expanded resonant cavity significantly reduces the laser linewidth and extends the laser coherence length required for long-range sensing. The OCL 1230 is placed on the rear surface 1208r of the substrate 1208 and is configured to collimate the laser light emitted by the VCSEL diode 1202 and collect the return laser light that returns from the target object towards the VCSEL diode 1202 and the first active region in the RCPD 1212. A reflective coating 1235 made of a dielectric material may be placed on the OCL 1230. In another example, a dielectric (multilayer) DBR can be placed on the OCL 1230 to form a mirror for the expanded resonant cavity.

[0126] In some examples, the OCL 1230 may be formed by etching the substrate 1208, resulting in a curved mirror. For example, the OCL 1230 may be formed using grayscale lithography, or the OCL 1230 may be formed using reflowed photoresist. In other examples, the OCL 1230 may be formed from a dielectric material by a reflow process. In some examples, the OCL 1230 may be a dielectric material or an organic material.

[0127] In some examples, a reflective coating can be deposited on the OCL 1230 to form a mirror for the extended cavity of the photoelectron sensing device 1200. In other examples, a dielectric (multilayer) DBR structure can be deposited on the OCL 1230 to form a mirror for the extended cavity of the photoelectron sensing device 1200.

[0128] The photoelectron sensing device 1200 may include an emitting (or "upper") DBR layer 1203a comprising a pair of alternating materials having different refractive indices (e.g., AlGaAs, GaAs). In addition, the MJ-VCSEL diode 1202 may also include a base-side DBR layer 1203b comprising a pair of Bragg pairs of alternating materials having different refractive indices (e.g., AlAs, GaAs). One or more of the materials in the emitting DBR layer 1203a and the base-side DBR layer 1203b may be p-type and n-type doped, respectively, thus forming parts of the anode and cathode portions of the pn diode structure, respectively.

[0129] The MJ-VCSEL diode 1202 may have multiple active regions 1207a, 1207b, and 1207c (for example, multiple pairs of barrier layers alternating with a quantum well layer) that generate laser light when stimulated by a forward bias voltage. Highly doped tunnel junctions 1210a and 1210b (similar to the tunnel junction 310 described above in relation to Figure 3) can be scattered in the multiple active regions 1207a, 1207b, and 1207c to form a vertically stacked multi-junction structure within the MJ-VCSEL diode 1202. One or more gain layers 1211a and 1211b (similar to the gain layer 311 described above in relation to Figure 3) can be coupled to the tunnel junctions 1210a and 1210b in the multi-junction structure within the MJ-VCSEL diode 1202, respectively. In the embodiment shown in Figure 12A, there are three active regions 1207a to 1207c, where two tunnel junctions 1210a and 1210b are scattered, each coupled to one of the two gain layers 1203a and 1203b. However, in other embodiments, the MJ-VCSEL diode 1202 may have two or more layers of each type that form a vertical stack between the DBR layers 1211a and 1211b.

[0130] Generally, in MJ-VCSEL diodes having different numbers of active regions, there is a tunnel junction between each successive pair of active regions. As shown in FIG. 12A, in MJ-VCSEL diode 1202, there is a first tunnel junction 1210a between active regions 1207a and 1207b, and a second tunnel junction 1210b between active regions 1207b and 1207c. Optionally, MJ-VCSEL diode 902 can also include one or more tunnel junctions (not shown) at locations other than between successive pairs of active regions 1207a to 1207c. The tunnel junctions 1210a, 1210b of MJ-VCSEL diode 1202 can be of the same type or different types. Semiconductor materials that can be used for the tunnel junction layer include GaAs, Al x Ga 1-x As, In x Ga 1-x As, In x Ga 1-x P, GaAs 1-x N x 、In x Ga 1-x As y P 1-y 、and others known to those skilled in the art. Depending on the polarity of the junction, the tunnel junctions 1210a, 1210b serve to improve carrier injection / extraction from MJ-VCSEL diode 1202 to RCPD 1212 and reduce the operating voltage of optoelectronic sensing device 1200.

[0131] Each of the active regions 1207a to 1207c includes a plurality of barrier layers and quantum well layers. Materials that can be used for the barrier layers of the active regions 1207a to 1207c include Al x Ga 1-x As(0 < x ≤ 1), GaAs 1-x P x (0 < x ≤ 1), and others known to those skilled in the art. Materials that can be used for the quantum wells of the active regions 1207a to 1207c include In x Ga 1-x As(0 < x ≤ 1), In x Ga 1-x As y N 1-y, (0 < x ≤ 1, 0 < y ≤ 1), In x Ga 1-x As 1-y-z N y Sb z (0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1), and others known to those skilled in the art.

[0132] The MJ-VCSEL diode 1202 includes a radiation side (or "upper") oxide layer 1209a disposed adjacent to the uppermost active region 1207a or on the upper surface of the MJ-VCSEL diode 1202, and a base side (or "bottom") oxide layer 1209c disposed adjacent to the lowermost active region 1207c or on the bottom surface of the MJ-VCSEL diode 1202. The oxide layer 1209c includes an opening (or openings) through which the primary radiation 1240 escapes. The MJ-VCSEL diode 1202 can also include an additional oxide layer 1209b adjacent to the active region 1207b. Each of the oxide layers 1209a and 1209b includes an opening (or openings) that allows the primary radiation 1240 to pass between the active regions 1207a - 1207c. Other embodiments of the MJ-VCSEL diode may not have an oxide layer between successive active regions, or may have two or more. The openings in the oxide layers 1209a - 1209c allow the laser light generated within the active regions 1207a - 1207c to pass through each other, enhancing the generation of the primary radiation 1240 of the laser light emitted through the optoelectronic sensing device 1200.

[0133] In some embodiments as shown in FIG. 12A, each of the active regions 1207a, 1207b, 1207c further includes one or more gain layer segments 1204a, 1204b, 1204c (e.g., InGaAs layer, AlGaAs layer) formed within the resonant cavity of the MJ-VCSEL diode 1202 to improve the efficiency of reabsorption of the primary radiation 1240 into the MJ-VCSEL diode 1202.

[0134] The radiating DBR layer 1203a, and then the RCPD 1212, may be formed by epitaxial growth of a layer on the substrate 1208, including the surface 1208f of the substrate 1208. Subsequently, the MJ-VCSEL diode 1202 can be formed on the RCPD 1212 by epitaxial growth. The base-side DBR layer 1203b may be formed on the MJ-VCSEL diode 1202 by epitaxial growth.

[0135] In some embodiments, the RCPD 1212 may include an active region 1214, which may include one or more gain layers (e.g., an InGaAs layer, an AlGaAs layer) to improve the absorption efficiency of the altered primary radiation 1240 after it has undergone self-mixing interference within the active regions 1207a-1207c of the VCSEL diode 902.

[0136] The MJ-VCSEL diode 1202 may have a common power supply contact 1205a located on or near the RCPD 1212 (shared with the RCPD 1212), a first power supply contact 1205b located on or near the radiating DBR layer 1203a, and a second power supply contact 1215a located on or near the base DBR layer 1203b. The common power supply contact 1205a, the first power supply contact 1205b, and the second power supply contact 1215a may each form a ring or horseshoe-shaped connection around the base DBR layer 1203b, the radiating DBR layer 903a, and the RCPD 912, respectively.

[0137] When a bias voltage is applied, the laser diode current I LD 1216 is the applied laser diode voltage V LD As a result, current may flow through the VCSEL diode 1202 between the common power supply contact 1205a and the second power supply contact 1215a, generating primary radiation 1240. This generates primary radiation 1240 directed toward a target object (not shown) through the substrate 1208 and OCL 1230. At the same time, current I PD1206 is the applied photodiode voltage V PD As a result, a reverse bias is generated through the RCPD 1212 by current flowing through the RCPD 1212 between the common power supply contact 1205a and the first power supply contact 1205b of the RCPD 1212. To enable a configuration for forward biasing the VCSEL diode 1202 and reverse biasing the RCPD 1212, one or more controllers, such as the processor 2104 described below with reference to Figure 21, can be communicated to the photoelectron sensing device 1200.

[0138] When the VCSEL diode 1202 is forward-biased, the laser light of the primary emission 1240 undergoes self-mixing interference within the laser cavity of the active region 1207a-1207c upon reflection or backscattering. The RCPD 1212 receives the self-mixed primary emission 1240 and, when reverse-biased, detects the altered electrical characteristics of the primary emission 1240.

[0139] The MJ-VCSEL diode 1202 can emit laser light with different characteristics than those emitted by a single-junction VCSEL (SJ-VCSEL) diode 302 (shown in Figure 3) operating at a similar current level. The MJ-VCSEL diode 1202 operates at an increased voltage level (compared to the SJ-VCSEL diode 302 operating at a similar current level), which can provide several factors, such as an increase in output power gain. It can also increase the center frequency of the emitted laser light, thereby improving the SNR by reducing 1 / f noise. The increased SNR and higher operating frequency also enable improved spatial resolution of the target by the photoelectronic sensing device 1200 having the MJ-VCSEL diode 1202, due to the increased efficiency and adjustable range for wavelength modulation of the laser light emitted by the MJ-VCSEL diode 1202, which in turn enables better measurement of electrical parameters related to the self-mixing interference of the emitted laser light. Therefore, the multi-junction structure within the MJ-VCSEL diode 1202 improves the performance of the photoelectronic sensing device 1200 through faster signal transmission, wider sampling, and reduced complexity.

[0140] In Figure 12B, the VCSEL diode 1202 may be forward-biased between the first bias node 1292 and the common node 1294, and the RCPD 1212 may be reverse-biased between the common node 1294 and the second bias node 1296. For example, the first bias node 1292 may be driven to a positive voltage, the common node 1294 may be driven to a lower positive voltage (e.g., ground), and the second bias node 1296 may also be driven to a positive voltage. In different embodiments, different voltage levels may be used for the first bias node 2392, the common node 1294, and the second bias node 1296. Forward-biasing the VCSEL diode 902 can drive a cathode load current that causes primary radiation 940a to 940c to radiate from the multi-junction structure 1201 having active regions 1207a to 1207c where tunnel junctions 1210a to 1210c are scattered. By reverse-biasing RCPD 1212, a photocurrent can be generated when RCPD 1212 receives primary radiation 1240a~1240c whose characteristics have been altered due to self-mixing in the VCSEL diode 1202. This photocurrent can be detected by a TIA connected to a second bias node 1296 or by another readout circuit. As described above, the multi-junction structure 1201 in Figure 12A increases the adjustability of thermal resistance and wavelength modulation for better measurement of self-mixing interference.

[0141] Figure 13A shows a perspective view of a first exemplary set of photoelectron sensing devices, such as a set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or Figures 12A-12B. Figure 13A schematically shows an example in which a set of photoelectron sensing devices 1320 (a bank of photoelectron sensing devices) shares a common photodiode bank contact and a common bank contact, and each photoelectron sensing device has a separate (e.g., addressable) power supply contact for a VCSEL diode.

[0142] The first exemplary set of photoelectron sensing devices shows eight examples of photoelectron sensing devices 1320 arranged in a 2x4 grid. Each photoelectron sensing device 1320 may be an example of a photoelectron sensing device 1200.

[0143] Each photoelectron sensing device 1320 has an associated power supply contact 1316. The power supply contact 1316 is a conductive material (e.g., a p-contact) electronically coupled to the first bias node of the VCSEL of the photoelectron sensing device 1320. In some examples, the power supply contact 1316 is an example of the first bias node 1292 and / or the second power supply contact 1215a.

[0144] A set of photoelectron sensing devices shares a common contact 1312 for the bank. The common contact 1312 is a conductive material that is electronically coupled to both the nodes of the VCSEL and the nodes of the RCPD, as will be described in more detail with reference to, for example, Figures 9A–9B or Figures 12A–12B. In some examples, the common contact 1312 is an example of a common node 1294 and / or a common power supply contact 1205a.

[0145] A set of photoelectron sensing devices shares a common photodiode contact 1314 for the bank. The common photodiode contact 1314 is a conductive material (e.g., n-contact) electronically coupled to the node of the RCPD, as will be described in more detail herein with reference to, for example, Figures 9A–9B or Figures 12A–12B. In some examples, the common photodiode contact 1314 is an example of a second bias node 1296 and / or a first power supply contact 1205b.

[0146] The common contact 1312, common photodiode contact 1314, and power supply contact 1316 are configured and oriented to be accessible for contact with conductors in order to provide electrical signals between the photoelectron sensing device and contacts of another device to which it may be bonded. As further described herein, the first face of a pair of photoelectron sensing devices is the light-emitting face of the device, and the first face is opposite the common contact 1312, common photodiode contact 1314, and power supply contact 1316. In some implementations, this contact arrangement can provide contact from drivers for the photoelectron sensing device to a two-dimensional set of addressable dots. Thus, in some cases, wire bonding and padding outside the array can be reduced or eliminated. Furthermore, the number of emitters per array can be increased, and a larger array of emitters can be utilized.

[0147] Figure 13B shows a cross-sectional view through cross-section A of Figure 13A. The layers of the photoelectron sensing device 1320 are generally electrically coupled to a common contact 1312, a common photodiode contact 1314, and a power supply contact 1316, as shown. The common contact 1312 can form a ring around the central portion of the photoelectron sensing device 1320.

[0148] Figure 14 shows a top view of an exemplary sensing array 1400 including a set of photoelectron sensing devices 1410. Figure 14 schematically shows an exemplary die architecture including an array of photoelectron sensing devices, where each set of photoelectron sensing devices (or bank) shares common contacts and common photodiode contacts.

[0149] A set of photoelectron sensing devices 1410 may be an example of a set of photoelectron sensing devices shown and described with reference to Figures 13A and 13B. The common contact 1412, common photodiode contact 1414, and power supply contact 1416 associated with photoelectron sensing device 1320 may be examples of the common contact 1312, common photodiode contact 1314, and power supply contact 1316 associated with photoelectron sensing device 1420. Photoelectron sensing device 1410 may be part of a larger bank 1402 of photoelectron sensing devices.

[0150] In some examples, the sensing array 1400 may be a single die. The sensing array 1400 includes 28 of a bank 1402 of 32 photoelectron sensing devices arranged in a set of 14 rows 1404 and 2 columns, including a first column 1406 and a second column 1408. Each bank 1402 (bank of photoelectron sensing devices) shares a common contact 1412 and a common photodiode contact 1414, and each photoelectron sensing device 1420 has a separate (e.g., addressable) power supply contact 1416 for a VCSEL diode.

[0151] Furthermore, as described above, the contacts of the sensing array 1400 are located on the surface opposite the light-emitting surface of the device and are configured and oriented to be accessible for contact with other devices such as drivers. Each photoelectron sensing device 1420 may have a width 1422 and a length 1424, including the area of ​​the photoelectron sensing device 1420. Since a bank of photoelectron sensing devices 1420 may share one of the common contacts 1412 and one of the common photodiode contacts 1414, the area of ​​bank 1402 can be reduced compared to other photoelectron sensing device architectures. For example, an architecture for a sensing array with an equivalent number of photoelectron sensing devices, where the contacts are routed around the die, may result in a larger area than that of the sensing array 1400. Similarly, an architecture for a sensing array with an equivalent number of photoelectron sensing devices, each with three contacts, may also result in a larger area than that of the sensing array 1400.

[0152] Figure 15A shows a perspective view of a second exemplary set of photoelectron sensing devices, such as the set of photoelectron sensing devices illustrated and described with reference to Figures 9A-9B or Figures 12A-12B. Figure 15A generally shows an example in which each photoelectron sensing device 1520 has an isolated photodiode. That is, each photodiode can be addressed and read separately, as opposed to the bank of photodiodes being read collectively, as shown and described with reference to Figures 13A-14, for example. Furthermore, each photoelectron sensing device 1520 has separate (e.g., addressable) power supply contacts for the VCSEL diode.

[0153] The first exemplary set of photoelectron sensing devices shows six examples of photoelectron sensing devices 1520 arranged in a 2x3 grid. Each photoelectron sensing device 1520 may be an example of a photoelectron sensing device 1200. In some examples, each photoelectron sensing device 1520 may be isolated from adjacent photoelectron sensing devices 1520 by a trench structure (e.g., an insulating trench). Each photoelectron sensing device 1520 may be an example of a photoelectron sensing device 1200.

[0154] Each photoelectron sensing device 1520 has an associated power supply contact 1516. The power supply contact 1516 is a conductive material (e.g., a p-contact) electronically coupled to the first bias node of the VCSEL of the photoelectron sensing device 1520. In some examples, the power supply contact 1516 is an example of the first bias node 1292 and / or the second power supply contact 1215a.

[0155] Each photoelectron sensing device 1520 also has associated common contacts 1512. The common contacts 1512 are conductive materials that are electronically coupled to both the nodes of the VCSEL and the nodes of the RCPD, as will be described in more detail with reference to, for example, Figures 9A-9B or Figures 12A-12B. In some examples, the common contacts 1512 are examples of common nodes 1294 and / or common power supply contacts 1205a.

[0156] Each photoelectron sensing device 1520 also has associated photodiode contacts 1514. The photodiode contacts 1514 are conductive materials (e.g., n-contacts) electronically coupled to the nodes of the RCPD, as will be described in more detail with reference to Figures 9A-9B or 12A-12B. In some examples, the photodiode contacts 1514 are examples of a second bias node 1296 and / or a first power supply contact 1205b.

[0157] The common contact 1512, photodiode contact 1514, and power supply contact 1516 are configured and oriented to be accessible for contact with conductors in order to provide electrical signals between the photoelectron sensing device and contacts of another device to which it may be bonded. As further described herein, the first face of a pair of photoelectron sensing devices is the light-emitting face of the device, and the first face is opposite the common contact 1512, photodiode contact 1514, and power supply contact 1516. In some implementations, this contact arrangement can provide contact from drivers for the photoelectron sensing device to a two-dimensional set of addressable dots. Thus, in some cases, wire bonding and padding outside the array can be reduced or eliminated. Furthermore, the number of emitters per array can be increased, and a larger array of emitters can be utilized.

[0158] Figure 15B shows a cross-sectional view through cross-section B of Figure 15A. The layers of the photoelectron sensing device 1520 are generally electrically coupled to a common contact 1512, a common photodiode contact 1514, and a power supply contact 1516, as shown. The common contact 1512 can form a ring around the central portion of the photoelectron sensing device 1520.

[0159] Figure 16 shows a top view of an exemplary sensing array 1600 of photoelectron sensing devices shown and described with reference to Figures 15A–15B. Figure 15A generally depicts an exemplary die architecture including an array of photoelectron sensing devices, where the three contacts of each photoelectron sensing device are individually accessible.

[0160] The photoelectron sensing device 1620 may be an example of the photoelectron sensing device 1520 shown and described with reference to Figures 15A to 15B. The common contact 1612, common photodiode contact 1614, and power supply contact 1616 associated with the photoelectron sensing device 1520 may be examples of the common contact 1512, common photodiode contact 1514, and power supply contact 1516 associated with the photoelectron sensing device 1620. The photoelectron sensing device 1620 may be part of a larger sensing array 1600.

[0161] In some examples, the sensing array 1600 may be a single die. The sensing array 1300 includes 30 photoelectron sensing devices arranged in a set of 5 rows 1601 and 6 columns 1606. Each photoelectron sensing device has individual (e.g., addressable) contacts, including a common contact 1612, a common photodiode contact 1614, and a power supply contact 1616.

[0162] Furthermore, as described above, the contacts of the sensing array 1600 are located on the surface opposite the light-emitting surface of the device and are configured and oriented to be accessible for contact with other devices such as drivers. Each photoelectron sensing device 1620 may have a width 1622 and a length 1624, including the area of ​​the photoelectron sensing device 1620. Since the photoelectron sensing devices 1420 can be accessed directly from bonded devices (e.g., driver chips), the area of ​​the sensing array 1600 can be reduced compared to other photoelectron sensing device architectures. For example, an architecture for a sensing array with an equivalent number of photoelectron sensing devices, where the contacts are routed around the die, may result in a larger area than that of the sensing array 1600.

[0163] Figure 17 is a top view of a first exemplary layout 1700 of a photoelectron sensing device, for example, a photoelectron sensing device, illustrated and described with reference to Figures 9A-9B or 12A-12B. The photoelectron sensing device 1710 may be one example of the photoelectron sensing devices shown and described with reference to Figures 9A-9B, 12A-12B, and 15A-16. Figure 17 generally shows an exemplary layout of an example of a photoelectron sensing device in which a common contact 1712 and a photodiode contact 1714 each form a ring around the central portion of the photoelectron sensing device 1710. The photoelectron sensing device 1710 may have an area defined by a length 1722 and a width 1724.

[0164] The common contact 1712, photodiode contact 1714, and power supply contact 1716 associated with the photoelectron sensing device 1710 may be examples of common contacts, common photodiode contacts, and power supply contacts associated with another photoelectron sensing device described herein, for example, the common contact 1512, common photodiode contact 1514, and power supply contact 1516 associated with the photoelectron sensing device 1520. The photoelectron sensing device 1520 may be formed as part of a larger sensing array, for example, sensing array 1600.

[0165] The common contact 1712 can generally form a first ring around the power supply contact 1716 for the photoelectron sensing device 1710. A portion of the common contact 1712 may extend away from the power supply contact 1716 and may be exposed so that the common contact can contact a conductor and form an electrical connection (e.g., to a chip driver bonded to an array of photoelectron sensing devices 1710). The unexposed portion of the common contact 1712 (e.g., including the ring portion closest to the power supply contact 1716) may be covered with a dielectric to protect the contact and prevent short circuits.

[0166] Similarly, the photodiode contact 1714 can generally form a second ring around the first ring of the common contact 1712 and the power supply contact 1716 of the photoelectron sensing device 1710. A portion of the photodiode contact 1714 may extend away from the power supply contact 1716 and may be exposed so that the common contact can contact a conductor and form an electrical connection. Non-exposed portions of the photodiode contact 1714 (e.g., including the ring portions closest to the first ring for the common contact 1712 and the power supply contact 1716) may be covered with a dielectric to protect the contact and prevent short circuits.

[0167] Figure 18 is a top view of a second exemplary layout 1800 of a photoelectron sensing device, such as the photoelectron sensing device illustrated and described with reference to Figures 9A-9B or 12A-12B. Figure 18 schematically shows an exemplary layout of an example of a photoelectron sensing device, in which a common contact 1712 forms a first half of a ring around the central portion of the photoelectron sensing device 1810, and a photodiode contact 1714 forms a second half of a ring around the central portion of the photoelectron sensing device 1810. In some examples, the first half of the ring and the second half of the ring may be in the same plane. In other examples, at least a portion of the first half of the ring may be in a different plane from at least a portion of the second half of the ring.

[0168] The common contact 1712, photodiode contact 1714, and power supply contact 1716 associated with the photoelectron sensing device 1810 may be examples of common contacts, common photodiode contacts, and power supply contacts associated with other photoelectron sensing devices described herein. The photoelectron sensing device 1820 may be formed as part of a larger sensing array.

[0169] The common contact 1712 may generally form the first half of a ring around the power supply contact 1716 for the photoelectron sensing device 1810. A portion of the common contact 1712 may extend away from the power supply contact 1716 and may be exposed to make contact with a conductor to form an electrical connection. The unexposed portion of the common contact 1712 (e.g., including the first half of the ring portion closest to the power supply contact 1716) may be covered with a dielectric to protect the contact and prevent short circuits.

[0170] Similarly, the photodiode contact 1714 can generally form a second half of a ring around the power supply contact 1716 for the photoelectron sensing device 1810. A portion of the photodiode contact 1714 may extend away from the power supply contact 1716 and may be exposed so that the common contact can contact a conductor and form an electrical connection. The unexposed portion of the photodiode contact 1714 (e.g., including the second half of the ring portion closest to the power supply contact 1716) may be covered with a dielectric to protect the contact and prevent short circuits.

[0171] The photoelectron sensing device 1810 may have an area defined by a length 1822 and a width 1824. The length 1822 or the width 1824 of the photoelectron sensing device 1810, or both, may be smaller than the length 1722 or width 1724 of a photoelectron sensing device 1710 that is otherwise similar or equivalent. Generally, a single segmented ring structure, as illustrated and described with reference to the photoelectron sensing device 1810, may have a relatively smaller area (and, for example, a relatively higher density) than two ring structures, as illustrated and described with reference to the photoelectron sensing device 1710.

[0172] The second exemplary layout 1800 shows a first half of the ring for the common contact 1712 and a second half of the ring for the photodiode contact 1714, although the ring may be divided according to different ratios. For example, the contact area to the photoelectron sensing device 1810 may be adjusted by changing the relative contact area between the common contact 1712 and the photodiode contact 1714, for example, by an amount greater than or less than half of the ring relative to one of the contacts or the other.

[0173] Figure 19 is a top view of the first array 1900 of a second exemplary layout of the photoelectron sensing device shown and described with reference to Figure 18. Figure 19 generally depicts a square or rectangular pattern (e.g., grid or array) of the photoelectron sensing device 1810, where the unit area conforms to a width of 1922 and a length of 1924. The photoelectron sensing device 1810 may be such as that shown and described with reference to the second exemplary layout 1800.

[0174] Figure 20 is a top view of a second array 2000 of a second exemplary layout of the photoelectron sensing device shown and described with reference to Figure 18. Figure 20 generally shows a hexagonal pattern (e.g., grid or array) of photoelectron sensing devices, including photoelectron sensing devices 2010 and 2020, with a unit area conforming to a width of 2022 and a length of 2024.

[0175] The photoelectron sensing devices 2010 and 2020 may be similar to, or different from, the photoelectron sensing device 1810 in the second exemplary layout 1800. In particular, the photoelectron sensing device 2010 may include the same central portion and a divided ring around the central portion, which includes a first half of the ring portion closest to the power supply contact 1716 and a second half of the ring portion closest to the power supply contact 1716. However, the portion of the common contact 1712 extending away from the power supply contact 1716 and the portion of the photodiode contact 1714 extending away from the power supply contact 1716 may be in different positions relative to the photoelectron sensing device 2010. In particular, these portions may generally be configured to enable the hexagonal pattern of the second array 2000. In some examples, the layout of the photoelectron sensing device 2010 is the same as the layout of the photoelectron sensing device 2020, but rotated by 180°. In other examples, the locations of the common contact 1712 and photodiode contact 1714 of the photoelectron sensing device 2010 may differ from those of the photoelectron sensing device 2020 (for example, they may be interchangeable).

[0176] In some examples, the unit area of ​​photoelectron sensing device 2010 (with a width of 2022 and a length of 2024) may be smaller than the unit area of ​​photoelectron sensing device 1810 (with a width of 1922 and a length of 1924). Therefore, in some examples, the second array 2000 of photoelectron sensing devices may be smaller than the first array 1900 of photoelectron sensing devices for the same number of devices (e.g., higher density, smaller pitch).

[0177] Figure 21 shows an exemplary electrical block diagram of an electronic device 2100 having a photoelectronic sensor, such as the photoelectronic sensing device described with reference to Figure 3. The electronic device 2100 may take the form of a handheld or portable device (e.g., a smartphone, tablet computer, or electronic watch), a vehicle navigation system, or the like. The electronic device 2100 may include an optional display 2102 (e.g., a light-emitting display), a processor 2104, a power supply 2106, a memory 2108 or storage device, a sensor system 2110, or an optional input / output (I / O) mechanism 2112 (e.g., an input / output device and / or input / output port). The processor 2104 may control some or all of the operation of the electronic device 2100. The processor 2104 may communicate directly or indirectly with substantially all components of the electronic device 2100. For example, a system bus or other communication mechanism 2114 can provide communication between the processor 2104, the power supply 2106, the memory 2108, the sensor system 2110, and the input / output mechanism 2112.

[0178] The processor 2104 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor 2104 may be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. As used herein, the term “processor” is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or one or more other appropriately configured computing elements.

[0179] It should be noted that in some embodiments, the components of the electronic device 2100 may be controlled by multiple processors. For example, selected components of the electronic device 2100 may be controlled by a first processor, and other components of the electronic device 2100 may be controlled by a second processor. Here, the first and second processors may or may not communicate with each other.

[0180] The power supply 2106 can be implemented by any device capable of supplying energy to the electronic device 2100. For example, the power supply 2106 may comprise one or more disposable or rechargeable batteries. In addition to or instead of this, the power supply 2106 may comprise a power connector or power cord for connecting the electronic device 2100 to another power source, such as a wall outlet.

[0181] Memory 2108 can store electronic data that can be used by the electronic device 2100. For example, memory 2108 may store electronic data or content, such as audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, maps, or focus settings. Memory 2108 can be configured as any type of memory. Just as an example, memory 2108 may be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

[0182] The electronic device 2100 may also include one or more photoelectronic sensors that define the sensor system 2110. The sensors can be placed substantially anywhere on the electronic device 2100. The sensors may be configured to detect substantially any kind of property, such as touch, force, pressure, electromagnetic radiation (e.g., light), heat, motion, relative motion, biometric data, distance, etc. For example, the sensor system 2110 may include touch sensors, force sensors, heat sensors, position sensors, light or optical sensors, accelerometers, pressure sensors (e.g., pressure transducers), gyroscopes, magnetometers, health monitoring sensors, image sensors, etc. In addition, one or more sensors may utilize any preferred sensing technique, including but not limited to capacitance, ultrasound, resistance, light, ultrasonic, piezoelectric, and thermal sensing techniques.

[0183] The I / O mechanism 2112 may transmit and / or receive data from a user or another electronic device. The I / O device may include a display, a touch-sensitive input surface such as a trackpad, one or more buttons (e.g., a graphical user interface "Home" button, or one of the buttons described herein), one or more cameras (including one or more image sensors), one or more microphones or speakers, one or more ports such as a microphone port, and / or a keyboard. In addition, or instead, the I / O device or ports may transmit electronic signals over a communication network such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular connections, Wi-Fi® connections, Bluetooth® connections, IR connections, and Ethernet connections. The I / O mechanism 2112 may also provide feedback (e.g., haptic output) to the user.

[0184] The preceding description uses certain technical terms for the sake of clarity and to provide a complete understanding of the described embodiments. However, it will be apparent to those skilled in the art that specific details are not necessary to carry out the described embodiments. Therefore, the preceding description of the specific embodiments described herein is presented for illustrative and explanatory purposes only. They are not intended to be exhaustive or to limit embodiments to the exact form disclosed. It will be apparent to those skilled in the art that, considering the above teachings, many modifications and variations are possible.

[0185] While the disclosed embodiments are illustrated and described in relation to one or more implementations, equivalent modifications and alterations will arise or will be known to those skilled in the art by reading and understanding this specification and the accompanying drawings. Furthermore, while the distinctive features of the present invention may be disclosed in relation to only one of several implementations, such features may be combined with one or more other features of other implementations so as to be desirable and advantageous for any given or particular application.

[0186] While various embodiments of this disclosure have been described above, it should be understood that these embodiments are presented merely as examples and are not limiting. Numerous modifications to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of this disclosure. Therefore, the breadth and scope of this disclosure should not be limited by any of the embodiments described above. Rather, the scope of this disclosure should be defined in accordance with the following claims and their equivalents.

Claims

1. A photoelectron sensing device, A first set of semiconductor layers disposed on a substrate, the first set of semiconductor layers including a first active region, and a vertical-cavity surface-emitting laser (VCSEL) diode at least partially defined by the first set of semiconductor layers, A second set of semiconductor layers, perpendicularly adjacent to the VCSEL diode and disposed on the substrate, wherein the second set of semiconductor layers includes a second active region, and the resonant cavity photodetector (RCPD) is at least partially defined by the second set of semiconductor layers. The device comprises a tunnel junction disposed between the first active region of the first set of semiconductor layers and the second active region of the second set of semiconductor layers, The VCSEL diode is configured to emit laser light toward the substrate when a first bias voltage is applied, and to be subject to self-mixing interference when the reflected or backscattered laser light is received. The RCPD is a photoelectron sensing device configured to detect the self-mixing interference during the emission of the laser light by the VCSEL diode when a second bias voltage is applied.

2. The photoelectron sensing device according to claim 1, wherein the VCSEL diode is disposed between the substrate and the RCPD.

3. The photoelectron sensing device according to claim 1, wherein the RCPD is disposed between the substrate and the VCSEL diode.

4. A first power supply contact disposed on or adjacent to one or more of the second set of semiconductor layers, A second power supply contact is disposed on or adjacent to one or more of the first set of semiconductor layers, The photoelectron sensing device according to claim 3, further comprising: a common power supply contact disposed on or in close proximity to the layer between the first active region of the first set of semiconductor layers and the second active region of the second set of semiconductor layers.

5. The photoelectron sensing device according to claim 4, wherein the photoelectron sensing device is a first photoelectron sensing device in a bank of an array of multiple photoelectron sensing devices, each photoelectron sensing device of the multiple photoelectron sensing devices shares a common photodiode bank contact coupled to the second power supply contact, and shares a common bank contact for the VCSEL diode coupled to the common power supply contact.

6. The photoelectron sensing device according to claim 4, wherein the photoelectron sensing device is a first photoelectron sensing device of an array of multiple photoelectron sensing devices, and each of the multiple photoelectron sensing devices has a photodiode contact coupled to the second power supply contact and a common contact for the VCSEL diode coupled to the common power supply contact.

7. The photoelectron sensing device according to claim 1, further comprising a controller configured to switch the bias polarity of the RCPD to capture multiple detections of the self-mixing interference in the time domain for time-multiplex sample readout.

8. A photoelectron sensing device, A substrate having a front surface and a back surface, A set of stacked semiconductor layers arranged on the surface, A vertical cavity surface-emitting laser (VCSEL) diode having a first active region within a resonant cavity, wherein the VCSEL diode is configured to emit primary radiation toward the substrate through the back surface when a first bias voltage is applied, A set of multilayer semiconductor layers defining a resonant cavity photodetector (RCPD) having a second active region offset from the first active region, A lattice structure arranged on the aforementioned set of stacked semiconductor layers, A photoelectron sensing device equipped with the following features.

9. The VCSEL diode is forward-biased during the primary emission. When the light emitted by the VCSEL diode during the primary emission receives reflection or backscattering of the primary emission, it undergoes self-mixing interference within the resonant cavity of the VCSEL diode. The photoelectron sensing device according to claim 8, wherein the RCPD is configured to detect the self-mixing interference when a second bias voltage is applied during the primary radiation by the VCSEL diode.

10. The photoelectron sensing device according to claim 8, wherein the lattice structure is arranged perpendicularly on the RCPD.

11. The photoelectron sensing device according to claim 8, wherein the VCSEL diode further includes a multijunction stack within the resonant cavity of the VCSEL diode, and the multijunction stack includes one or more gain layers interconnected with one or more vertically stacked tunnel junction layers.

12. The photoelectron sensing device according to claim 11, wherein the VCSEL diode further comprises one or more oxide layers formed on the upper surface of the VCSEL diode, on the bottom surface of the VCSEL diode, or within the multi-junction stack, and each of the one or more oxide layers defines one or more oxide openings.

13. The photoelectron sensing device according to claim 11, wherein the substrate defines at least a portion of an expanded laser cavity separated from the multi-junction stack of the VCSEL diode by a pair of distributed Bragg reflector (DBR) layers formed on the substrate.

14. The photoelectron sensing device according to claim 8, wherein the RCPD comprises one or more gain layers disposed within the resonant cavity of the RCPD, and the one or more gain layers contain indium gallium arsenide.

15. The on-chip lens arranged on the back surface of the substrate, The photoelectron sensing device according to claim 8, further comprising: a reflective coating disposed on the on-chip lens and configured to reflect back a portion of the primary radiation toward the first active region.

16. The photoelectron sensing device according to claim 8, wherein the lattice structure is filled with a dielectric material comprising one of silicon oxide, aluminum oxide, and silicon nitride.

17. A photoelectron sensing device, A substrate having a front surface and a back surface, A set of stacked semiconductor layers arranged on the aforementioned surface, One or more mesas of the first set, where each mesa within the one or more mesas of the first set is A vertical-cavity surface-emitting laser (VCSEL) diode having a first active region within the resonant cavity of the VCSEL diode, configured to emit primary radiation toward the substrate through the back surface when a first bias voltage is applied, A first set of one or more mesas, including a resonant cavity photodetector (RCPD) having a second active region offset from the first active region, and configured to detect self-mixing interference of the primary radiation in the laser cavity of the VCSEL diode upon reception of reflection or backscatter when a second bias voltage is applied, A set of multilayer semiconductor layers defining a set of mesa, including one or more mesa of a second set, At least one conductor electrically connected to an element of a first mesa in one or more mesa of the first set and routed over a portion of a second mesa in one or more mesa of the second set, A photoelectron sensing device equipped with the following features.

18. The photoelectron sensing device according to claim 17, wherein at least two adjacent mesas are operably separated by trenches etched through the pair of multilayer semiconductor layers, and the conductor of at least one of the conductors is located within the trenches.

19. The photoelectron sensing device according to claim 18, wherein the trench extends into the substrate through the pair of multilayer semiconductor layers.

20. The photoelectron sensing device according to claim 17, wherein the at least one conductor allows RCPDs in one or more mesas of the first set to be individually addressable.

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