Optoelectronic device and system for optical data transmission

Abstract

The invention relates to an optoelectronic device, in particular a combined micro-LED and a micro-detector, comprising a substrate and a semiconductor layer stack arranged on the substrate. The semiconductor layer stack comprises a first layer, a second layer, a third layer, a first active region between the first and second layers, and a second active region between the second and third layers. The first and second layers are doped with a first conductivity type, and the third layer is doped with a second conductivity type that differs from the first conductivity type. Furthermore, the second layer has a higher doping concentration of the first conductivity type than the first layer, and the first active region has a smaller band gap than the second active region.

Description

[0001] The present application claims priority from German patent application DE 10 2023 113 465.5, filed on May 23, 2023, the disclosure of which is included in its entirety by reference.

[0002] The present invention relates to an optoelectronic device, an arrangement of optoelectronic devices, and a system for optical data transmission. The present invention further relates to a method for operating an optoelectronic device and for operating a system for optical data transmission. BACKGROUND

[0003] Today's internet relies on large data centers. However, their high energy consumption poses a problem when it comes to ensuring their operation is powered exclusively by sustainable energy sources. Most of the electricity is not used for computations, but for data transmission over short distances (< 10 m): from the CPU to the GPU, from server to server, from rack to rack.

[0004] Currently, short-distance data transmission is achieved either electrically, primarily via copper (Cu) or aluminum (Al) leads and cables (within the chip or motherboard), or optically by combining near-infrared (NIR) vertical surface emitter lasers (VCSELs) with optical fibers. However, the metals cause electrical power losses due to their resistivity, and the VCSELs, on the other hand, require a certain threshold current (I). th), to initiate laser emission, typically in the mA range. Together with the required forward voltage, this threshold current I defines th ) a dissipated (electrical) power of a few mW.

[0005] To reduce power consumption for short-distance optical data transmission, efforts are underway to utilize micro-LEDs to address the problem of high power consumption. Micro-LEDs offer the advantage of operating at very low currents (1–500 µA per pixel), which are significantly lower than those of lasers such as VCSELs, and they do not require a (laser) threshold to be exceeded. Furthermore, micro-LEDs have a small footprint (less than 5 µm is possible) and can be integrated onto backplane wafers using common display technologies. This allows for high parallelization during micro-LED transmission, further reducing power consumption during hardware manufacturing.

[0006] The use of small optoelectronic components such as µ-LEDs for optical data transmission therefore offers significant advantages over, for example, VCSEL technology due to better scalability and lower power consumption, and saves energy, especially for data transmission over short and medium distances.

[0007] The use of small optoelectronic components such as micro-LEDs requires not only high quantum efficiency but also very fast emitter switching to enable high data rates. A limitation in this regard is the lifetime of radiative recombination, which limits the rise and fall times of light emission when modulating or switching the micro-LED on / off. This effect is particularly significant when using micro-LEDs due to their large surface-to-volume ratio.

[0008] Currently known approaches to reducing the lifetime of radiative recombination include, for example, background doping (e.g., in the QW barriers) to increase the charge carrier density for certain charge carrier types, the use of quantum dots, and / or attempts to achieve a high current density.

[0009] However, these methods can only improve the performance of optoelectronic components to a certain extent.

[0010] Therefore, one of the objectives of the present application is to provide an optoelectronic component and a system for optical data transmission that counteracts at least some of the aforementioned disadvantages. SUMMARY OF THE INVENTION

[0011] These and other tasks are addressed by the subject matter of the independent claims. Features and further aspects of the proposed principles are set out in the dependent and subsidiary claims.

[0012] The core of the invention is to provide an optoelectronic component and a system using such optoelectronic components, enabling the transmission of data back and forth over a single optical fiber. This can be achieved by using monolithically integrated micro-LEDs and micro-detectors as the optoelectronic components. Depending on the operating mode, the optoelectronic devices can be used either as emitters or as detectors, allowing for their "universal" use. This reduces the space requirements of such a system.

[0013] The basic concept is to provide a semiconductor stack with a suitable arrangement of different layers, configured to emit light of a desired wavelength when forward-biased and to detect light of a desired wavelength when 0 V biased or reverse-biased. The semiconductor stack comprises a first layer of a first conductivity type, a second layer of the same conductivity type, and a third layer of a second conductivity type that differs from the first. The semiconductor stack further includes a first active region between the first and second layers and a second active region between the second and third layers, the first active region having a smaller bandgap than the second active region.The second layer acts as a spacer layer with a higher doping concentration of the first conductivity type than the first layer.

[0014] A forward bias on the semiconductor stack causes the space charge region to close, so that holes recombine with electrons only in the second active region and emit light with the energy of the band gap of the second active region. Conversely, a 0 V bias on the semiconductor stack causes the space charge region to remain so that it covers the second active region. Light with an energy greater than (and including) the band gap of the second active region can then be detected within the second active region. Finally, a reverse bias on the semiconductor stack causes the space charge region to expand so that it covers not only the second active region but also the first active region.Light with an energy greater than the band gap of the first active region (inclusive) can then be detected over the entire enlarged space charge region.

[0015] In a first aspect, an optoelectronic device, in particular a combined micro-LED and a micro-detector, is provided. The optoelectronic device comprises a substrate and a semiconductor layer stack arranged on the substrate. The semiconductor layer stack comprises a first layer, a second layer, a third layer, a first active region between the first and second layers, and a second active region between the second and third layers. The first and second layers include a doping of a first conductivity type, with the second layer having a higher doping concentration than the first layer, and the third layer includes a doping of a second conductivity type that differs from the first conductivity type.For example, the first and second layers can be n-doped and the third layer p-doped, but the order can also be reversed. Furthermore, the first active region has a smaller band gap than the second active region. The active regions can, for example, each contain a quantum well or multiple quantum well structure.

[0016] In some aspects, the optoelectronic device is configured to emit light when a forward voltage is applied between the first and third layers / to the semiconductor stack, and to detect light when a voltage of 0 V or a reverse voltage is applied between the first and third layers / to the semiconductor stack. If the first and second layers have n-type doping and the third layer has p-type doping, a forward voltage can mean a voltage greater than 0 V applied between the first and third layers, and a reverse voltage can mean a voltage less than 0 V applied between the first and third layers. This results in the semiconductor stack being forward-biased or reverse-biased, respectively.

[0017] In some aspects, the optoelectronic device is a combined micro-LED and micro-detector. Such a combined micro-LED and micro-detector can, in particular, be a device with edge lengths of less than 100 µm, less than 50 µm, less than 20 µm, less than 10 µm, or less than 5 µm, configured to emit and detect light of a desired wavelength.

[0018] In some aspects, the optoelectronic device further comprises an upper contact element that is in electrical contact with the third layer and a lower contact element that is in electrical contact with the first layer.

[0019] At least one of the upper or lower contact elements can be substantially transparent to light with an energy less than or equal to the band gap of the second active region. In particular, the upper or lower contact element can form a light-emitting and / or light-absorbing region of the optoelectronic device through which light generated in the second active region is coupled out of the optoelectronic device and / or through which light is coupled into the optoelectronic device for detection. Such a substantially transparent contact element can be formed, for example, from a transparent conductive oxide (TCO) such as indium tin oxide (ITO). The light-emitting / light-absorbing region can be formed either by the upper or lower contact element itself, or by other structures / elements as described later herein.

[0020] In some aspects, the other of the upper and lower contact elements, which is not essentially transparent, includes a reflective material layer covering the underlying layers of the first and third layers. In the case of the upper contact element, the reflective material layer can cover the third layer opposite the second active area, or in the case of the lower contact element, the reflective material layer can cover the first layer opposite the first active area. This allows for directed emission of the generated light towards the light-emitting area and more efficient extraction of the generated light by the light-emitting area.On the other hand, the detection efficiency of the optoelectronic device can be increased because light that has not yet been detected but has been propagated through the semiconductor layer stack is reflected within the optoelectronic device in order to possibly be detected "on a further attempt" when it is propagated back through the semiconductor layer stack.

[0021] In some aspects, the upper contact element comprises a first region and a second region, spaced apart from each other on the third layer opposite the second active region. In some aspects, the lower contact element comprises a first region and a second region, spaced apart from each other on the first layer opposite the first active region. The separate regions of the upper and / or lower contact element can, for example, form separate electrical contacts to control an emitter and a detector region of the optoelectronic device independently.

[0022] In some aspects, the semiconductor layer stack comprises an emitter region and a detector region, wherein the emitter region includes at least a region of the second active region and the third layer, and wherein the detector region includes at least a region of the first layer and the first active region. In the detector region, for example, the second active region and the third layer, and optionally the second layer, can be removed. In the emitter region, on the other hand, for example, the first layer and the first active region, and optionally the second layer, can be removed. The emitter region and the detector region can, for example, be separated from each other by a gap.

[0023] In some aspects, for example, the second active region and the third layer, and optionally the second layer, can be partially removed, so that the semiconductor stack forms a step with the first layer and the first active region, and optionally the second layer, forming a base on which a stub of the second active region and the third layer, and optionally the second layer, is placed. The portion of the semiconductor stack encompassing the stub can thus form the emitter region, while at least the region of the semiconductor stack surrounding / adjacent to the stub, and in particular the entire base of the semiconductor stack, can form the detector region.

[0024] In some aspects, for example, the first active region and the first layer, and optionally the second layer, can be partially removed, so that the semiconductor stack forms a step with the third layer, and the second active region and optionally the second layer form a base on which a stub of the first active region and the first layer, and optionally the second layer, is placed. The portion of the semiconductor stack that includes the stub can form the detector region, while at least the region of the semiconductor stack that surrounds / adjacents the stub, and in particular the entire base of the semiconductor stack, can form the emitter region.

[0025] In both of the aforementioned cases, the emitter region and the detector region can be separated from each other, for example, by a slit. However, the emitter region and the detector region can also be connected to each other, for example, via their common base.

[0026] The semiconductor layer stack can have any shape, for example, a truncated pyramid with angled sides or a truncated cylindrical shape with angled sides. Such angled sides can result, for example, from a mesa etching process. However, the semiconductor layer stack can also include a step with a base of the semiconductor layer stack having a larger cross-section than, for example, a truncated stack, which is / are arranged on the base. In such a case, the truncated stack can be, for example, centered on the base or arranged along one of the sides of the base. The base and / or the truncated stack can each again have any shape, for example, a truncated pyramid with angled sides or a truncated cylindrical shape with angled sides.These exemplary embodiments are not to be understood as limiting, but merely as possible embodiments. Other arrangements, shapes, and cross-sections are also possible.

[0027] In some aspects, the semiconductor stack comprises a plurality of emitter regions and a detector region, wherein the emitter regions include at least one region of the second active region and the third layer. Within the emitter regions, for example, the first layer and the first active region, and optionally the second layer, can be removed, such that the semiconductor stack forms steps. The first layer and the first active region, and optionally the second layer, form a base upon which stubs of the second active region and the third layer, and optionally the second layer, are arranged. The portions of the semiconductor stack that comprise a stub can form the emitter portions, while at least the region of the semiconductor stack surrounding / adjacent to the stubs, and in particular the entire base of the semiconductor stack, can form the detector portion.The emitter and detector sections can be separated from each other, for example, by a gap. This allows for redundancy between the emitters in case one or more emitter sections fail.

[0028] In some aspects, the optoelectronic device further comprises a central contact element that is in electrical contact with the second layer and / or the first or second active region. In particular, if the semiconductor layer stack is partially removed to form the emitter and detector regions, the central contact element can form another contact element located on the recessed layer / active region. If the central contact element is located directly on the first or second active region, it can be a Schottky contact element in electrical contact with the respective active region. Therefore, the emitter and detector regions can be operated separately by applying a voltage between the upper and lower contact elements and a voltage between the central contact element and the first or second active region, respectively.The third contact element is created.

[0029] Therefore, in some aspects, the optoelectronic device is configured to emit light when a forward voltage is applied between the upper and lower contact elements, and it is configured to detect light when a voltage of 0 V or in the reverse direction is applied between the lower and middle contact elements. In other aspects, the optoelectronic device is configured to emit light when a forward voltage is applied between the upper and middle contact elements, and it is configured to detect light when a voltage of 0 V or in the reverse direction is applied between the lower and upper contact elements.

[0030] In some aspects, the optoelectronic device includes a reflective coating extending along the side faces of the semiconductor layer stack. This allows, for example, the directed emission of light generated within the semiconductor layer stack towards the light-emitting region and more efficient extraction of the generated light from the light-emitting region. Furthermore, the detection efficiency of the optoelectronic device can be increased because light propagated through the semiconductor layer stack but not yet detected is reflected within the stack, potentially to be detected on a subsequent attempt when it propagates back through the stack.

[0031] In some aspects, a dielectric material or dielectric layer is positioned between the side faces of the semiconductor layer stack and the reflective coating. This prevents a short circuit within the optoelectronic device that could be caused by the reflective coating if it electrically connects the first, optional middle and top contact element.

[0032] In some aspects, the optoelectronic device further comprises an output coupling structure on the upper contact element relative to the substrate, or on the lower contact element relative to the substrate, and / or on the middle contact element relative to the substrate. The output / input coupling structure forms, for example, the light-emitting / light-incident region. The output / input coupling structure can be, for example, a surface roughening of the upper / lower / middle contact element or of an additional layer arranged on the upper / lower / middle contact element. In this way, the output and / or input of light to and from the optoelectronic device can be improved, as can the directional dependence of the output light. Furthermore, this can improve the input of light into an adjacent optical fiber.

[0033] In some aspects, the optoelectronic device further comprises an optical element on the upper contact element opposite the substrate, or on the lower contact element opposite the substrate, and / or on the middle contact element opposite the substrate. The optical element can be, for example, a microlens or a photonic structure. This improves the coupling of light out of and / or into the optoelectronic device, as well as the directional dependence of the coupled-out light. Furthermore, it can improve the coupling of light into an adjacent optical fiber.

[0034] In some aspects, the substrate includes a supply circuit that is in electrical contact with the upper and / or lower and / or middle contact element. The substrate can, for example, be in the form of a CMOS element or a portion of a CMOS wafer.

[0035] In some aspects, the support substrate is connected to extensions of the lower, middle, and upper contact elements, or directly to at least the lower contact element and, in particular, to the middle and upper contact elements. However, the support substrate can also be monolithically integrated with the semiconductor layer stack and the contact elements. It is also conceivable that the optoelectronic device does not include a support substrate and is subsequently deposited onto a suitable support substrate.

[0036] In some aspects, optoelectronic devices can be processed according to the proposed principle as individual elements that can, for example, be transfer-printed or transferred onto a substrate. However, in other aspects, optoelectronic devices can also be processed according to the proposed principle as an array / plurality of optoelectronic devices arranged adjacent to one another on a substrate, forming an assembly.

[0037] In another aspect, an arrangement is provided that comprises a support substrate and a multitude of optoelectronic devices, arranged adjacent to each other on a common support substrate, according to some aspects of the proposed principle. In some aspects, the optoelectronic devices are arranged in an array in rows and columns and, for example, connected with a filler material, such as a polymer filler. The filler material can, for example, optically isolate the optoelectronic devices from one another.

[0038] The monolithic integration of emitters and detectors, as described above, enables the fabrication of a compact and well-aligned array of optoelectronic devices. Furthermore, the use of vias for vertical stacking allows for very short connections to a substrate, such as a CMOS driver.

[0039] In another aspect, a system for optical data transmission is provided, comprising a first arrangement of optoelectronic devices and a second arrangement of optoelectronic devices. The optoelectronic devices of the first arrangement are optically coupled to a corresponding optoelectronic device of the second arrangement to transmit optical data. Each optoelectronic device of the first and second arrangements comprises an emitter and a detector region, so that data can be transmitted back and forth between the two arrangements via a single optical path. At least one of the first and second arrangements is an arrangement according to some of the aspects mentioned above.

[0040] In some aspects, the optoelectronic devices of the first arrangement are configured to emit light of a first wavelength, and the optoelectronic devices of the second arrangement are configured to detect the first-wavelength light emitted by the respective optoelectronic device of the first arrangement. Thus, the first arrangement is configured to transmit optical data, and the second arrangement is configured to detect optical data. Furthermore, the optoelectronic devices of the second arrangement are configured to emit light of a second wavelength, and the optoelectronic devices of the first arrangement are configured to detect the second-wavelength light emitted by the respective optoelectronic device of the second arrangement.Thus, the second arrangement is also configured to transmit optical data, and the first arrangement is configured to detect optical data. For optical data transmission, only one arrangement is configured to send and receive optical data on each side of the communicating objects, and communication between the communicating objects is achieved by sending and receiving data at different times or, if the first and second wavelengths are different, by sending and receiving data with different wavelengths simultaneously.The optoelectronic devices of the first arrangement are therefore configured, for example, to emit light of a first wavelength at a first time, and the optoelectronic devices of the second arrangement are configured to detect the light of the first wavelength emitted by the respective optoelectronic device of the first arrangement at the first time. Furthermore, the optoelectronic devices of the second arrangement are configured to emit light of the second wavelength at a second time, and the optoelectronic devices of the first arrangement are configured to detect the light of the second wavelength emitted by the respective optoelectronic device of the second arrangement at the second time.

[0041] In some aspects, the first and second wavelengths are essentially the same, and thus the first and second arrangements comprise essentially the same optoelectronic devices. However, in some aspects, the first and second wavelengths differ. In the latter case, a filter for the first wavelength can be placed over each detector area of ​​the optoelectronic devices of the first arrangement, and a filter for the second wavelength can be placed over each detector area of ​​the optoelectronic devices of the second arrangement. The filter for the first wavelength can be configured to transmit light of the second wavelength but block light of the first wavelength, and the filter for the second wavelength can be configured to transmit light of the first wavelength but block light of the second wavelength.

[0042] In another aspect, a method for operating an optoelectronic device according to some aspects of the proposed principle is provided. The method comprises the following steps: Applying a forward voltage between the third layer and the first or second layer to emit light of a first wavelength; Coupling of the light of the first wavelength from the optoelectronic device by means of a light emission region located on one side of the semiconductor layer stack opposite the substrate; Applying a voltage of 0V or in reverse direction between the first layer and the third or second layer to detect light of a second wavelength falling on a light incidence area of ​​the optoelectronic device located on one side of the semiconductor layer stack opposite the substrate.

[0043] In some aspects the first and second wavelengths are essentially the same, but in some aspects the first and second wavelengths differ from each other.

[0044] In another aspect, a procedure for operating a system according to some aspects of the proposed principle is provided. The procedure comprises the following steps: Emitting light of a first wavelength by means of a first optoelectronic device of the first arrangement; Coupling the light of the first wavelength into a first optical fiber; Transmission of the light of the first wavelength to a corresponding first optoelectronic device of the second arrangement; Coupling the light of the first wavelength into the first optoelectronic device of the second arrangement; and Detection of the light of the first wavelength using the first optoelectronic device of the second arrangement.

[0045] In some aspects, the procedure also includes the following steps: Emitting light of a second wavelength by means of the first optoelectronic device of the second arrangement; Coupling the light of the second wavelength into the first optical fiber; Transmission of the light of the second wavelength to the first optoelectronic device of the first arrangement; Coupling the light of the second wavelength into the first optoelectronic device of the first arrangement; and Detection of the light of the second wavelength using the first optoelectronic device of the first arrangement. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Further aspects and embodiments according to the proposed principle will become clear with reference to the various embodiments and examples, which are described in detail in connection with the accompanying drawings, in which Fig. 1 shows an embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. 2 illustrates the space charge region of an optoelectronic device according to some aspects of the proposed principle as a function of a voltage applied to it; Fig. 3 shows another embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. 4 shows a further embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. Figure 5 shows another embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. 6A and Fig. 6B shows a cross-section and a top view of a further embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. Figure 7 shows a top view of another embodiment of an optoelectronic device according to some aspects of the proposed principle; Fig. Figure 8 shows an embodiment of an arrangement with a plurality of optoelectronic devices according to some aspects of the proposed principle; Fig. 9A and Fig. 9B Show steps of a method for operating an optoelectronic device according to some aspects of the proposed principle; Fig. 10 shows an embodiment of a system for optical data transmission according to some aspects of the proposed principle; and Fig. Figure 11 shows another embodiment of a system for optical data transmission according to some aspects of the proposed principle. DETAILED DESCRIPTION

[0047] The following embodiments and examples reveal various aspects and their combinations according to the proposed principle. The embodiments and examples are not always to scale. Likewise, various elements may be enlarged or reduced to highlight individual aspects. It is understood that the individual aspects of the embodiments and examples shown in the figures can readily be combined without contradicting the principle of the invention. Some aspects have a regular structure or shape. It should be noted that in practice, minor differences and deviations from the ideal form may occur without contradicting the inventive concept.

[0048] Furthermore, the individual figures and aspects are not necessarily depicted in the correct size, nor do the proportions between individual elements need to be essentially accurate. Some aspects are emphasized through magnification. However, terms such as "above," "over," "below," "under," "larger," "smaller," and the like are correctly represented in relation to the elements within the figures. Thus, it is possible to deduce such relationships between the elements based on the figures.

[0049] Fig. Figure 1 shows a first embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. The optoelectronic device 1 comprises a semiconductor layer stack 2 arranged on a support substrate 13. The semiconductor layer stack 2 comprises a first layer 3a, a second layer 3b, and a third layer 3c. The semiconductor layer stack 2 further comprises a first active region 4a between the first and second layers 3a, 3b, and a second active region 4b between the second and third layers 3b, 3c. The first and second layers 3a, 3b comprise doping of the same conductivity type, wherein the second layer has a higher doping concentration and the third layer comprises doping of a different conductivity type. For example, the first and second layers are n-doped layers, while the second layer is a p-doped layer, or vice versa.

[0050] In the embodiment shown, the optoelectronic device 1 further comprises a lower contact element 6, which is electrically in contact with the first layer 3a, and an upper contact element 8 (not shown), which is electrically in contact with the third layer 3c.

[0051] As on the right in Fig. As shown in Figure 1, the first active region 4a has a smaller band gap than the second active region 4b, or at least a substantially equal band gap. Therefore, the energy E g det of the first active area 4a smaller than or at least substantially equal to the energy E g Emitter of the second active area 4b. In addition, the active areas 4a, 4b, as shown on the right in Fig. Figure 1 shows a multiple quantum well structure.

[0052] Fig. Figure 2 shows the space charge region d of the optoelectronic device 1. Fig. 1 depending on an applied voltage. When a voltage V of 0 V is applied between the first and third layers 3a, 3c, and thus a bias voltage of 0 V of the semiconductor layer stack 2, the space charge region d extends from the second region 3b into the third region 3c and includes the second active region 4b (see a) of Fig. 2) In this state, for example, light with an energy E can then be emitted. g Emitter Larger than the band gap of the second active region 4b (inclusive) are detected in the second active region 4b. A forward bias of the semiconductor layer stack 2 causes the space charge region d to close such that holes recombine with electrons only in the second active region 4b and emit light with energy E. g Emitter of the second active area 4b emit (see b) in Fig. 2) A reverse bias of the semiconductor layer stack 2 causes the space charge region d to increase so that it covers not only the second active region 4b but also the first active region 4a. Light with an energy E g det , which is larger than the band gap of the first active region 4a (inclusive), can then be applied over the entire enlarged space charge region d (see c) in Fig. 2) be detected.

[0053] Fig. Figure 3 shows a further embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. In addition to the aforementioned embodiment, the optoelectronic device 1 comprises an upper contact element 8 on the third layer 3c for electrically contacting the semiconductor layer stack 2 and, in particular, the third layer 3c. The upper contact element 8 comprises a first region 8a and a second region 8b, which are spaced apart from each other on the third layer 3c. The first and second regions 8a, 8b form separate electrical contacts for operating an emitter region 9 and a detector region 10 of the optoelectronic device 1.

[0054] To operate the emitter region 9, a forward voltage V1 is applied between the first region of the upper contact element 8a and the lower contact element 6, and light with an energy E is emitted. gEmitter The second active region 4b can emit light via a light-emitting region 17 above the emitter region 9. The light-emitting region 17 can, in particular, be formed by the first region of the upper contact element 8a, which therefore consists, for example, of a material that is suitable for at least the light with energy E. g Emitter of the second active area 4b is essentially transparent.

[0055] To operate detector area 10, a blocking voltage V2 is applied between the second area of ​​the upper contact element 8b and the lower contact element 6, and light with an energy E g detThe light intensity, which is larger than the band gap of the first active region 4a (inclusive) and which falls on a light incidence region 17 above the detector region 10, can be detected in the enlarged space charge region. The light incidence region 17 can, in particular, be formed by the second region of the upper contact element 8b, which therefore consists, for example, of a material that is at least suitable for light with an energy E g det larger than the band gap of the first active region 4a (inclusive) is essentially transparent.

[0056] Additionally, the lower contact element 6 can include a reflective material layer covering the first layer 3a. This enables directed emission of the generated light towards the light-emitting region 17 and more efficient coupling of the generated light through the light-emitting region 17. Furthermore, the detection efficiency of the optoelectronic device 1 can be increased because light that has not yet been detected but has propagated through the semiconductor layer stack 2 is reflected within the optoelectronic device 1, potentially to be detected "on a subsequent attempt" when it propagates back through the semiconductor layer stack 2.

[0057] Fig. Figure 4 shows a further embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. In contrast to the aforementioned embodiment, the optoelectronic device 1 comprises a "separate" emitter region 9 and a detector region 10. This is achieved by removing portions of the third layer 3b, the second active region 4b, and the second layer 3b in the detector region 10. However, the removal of the second layer 3b is optional, and the second layer 3b can also remain on the first active region 4a. In the embodiment shown above, a central contact element 7 is arranged on the first active region 4a, which in this case has the form of a Schottky contact element. If the second layer 3b remains on the first active region 4a, any other material / element can be used for the central contact element 7.

[0058] As in the embodiment mentioned above, the emitter area 9 and the detector area can be operated by applying a forward and reverse voltage V1, V2.

[0059] Fig. Figure 5 shows a further embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. In contrast to the embodiment mentioned above, none of the layers of the semiconductor stack 2 are removed in the detector region 10 of the optoelectronic device 1, while in the emitter region 9 the first layer 3a, the first active region 4a, and optionally the second layer 3b are removed. In the embodiment shown, a central contact element 7 is arranged on the second layer 3b, which in this case consists of a material that is effective for at least light with energy E. g Emitter of the second active area 4b is essentially transparent.

[0060] In contrast to the aforementioned embodiments, the semiconductor layer stack 2 on the support substrate 13 is arranged in reverse, with the upper contact element 8 facing the support substrate 13. In this case, the upper contact element 8 comprises a reflective material layer covering the third layer 3c, and the lower contact element 6 on the first layer 3a in the detector region 10 comprises a material that is reflective, at least for light with an energy E g det , which is larger than the band gap of the first active region 4a (inclusive), is essentially transparent. The light-emitting region 17 can then be formed in particular by the middle contact element 7, and the light-receiving region 17 can be formed in particular by the lower contact element 6.

[0061] To further "separate" the emitter region 9 and the detector region 10, a gap 11 can be formed between the two regions. However, the structure and material composition of the layers of the emitter and detector regions 9 and 10 are identical, since the gap 11 is only created after the layers have grown on top of each other.

[0062] Fig. Figure 6A shows another embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. In contrast to the one in Fig. In the embodiment shown in section 4, the optoelectronic device 1 comprises several adjacent emitter regions 9. As in the embodiment of Fig. 4. Parts of the third layer 3b, the second active region 4b, and the second layer 3b are removed to form the detector region 10, on which the central contact element 7 is arranged. The emitter region 9 of the embodiment of Fig. However, 4 is divided into several areas separated by a gap, up to the first active area 4a, each forming a separate emitter area 9. Each emitter area comprises a section of the upper contact element 8a, 8b, to allow the emitter areas 9 to operate separately. This enables, for example, redundancy between the emitter areas 9.

[0063] Fig. Figure 6B shows an exemplary top view of the embodiment of the optoelectronic device 1. Fig. 6A. The optoelectronic device 1 comprises four emitter regions in a “corner” of the semiconductor layer stack 2 and a detector region 10 extending along the opposite sides of the “corner” of the semiconductor layer stack 2. However, the construction and arrangement shown are only to be understood as an example.

[0064] Fig. Figure 7 shows an alternative top view of an embodiment of an optoelectronic device 1 according to some aspects of the proposed principle. The optoelectronic device 1 comprises two emitter regions arranged in the center of the semiconductor layer stack 2, and a detector region 10 surrounding the emitter regions. Furthermore, the semiconductor layer stack is surrounded by a filler material 16 extending along the side faces of the semiconductor layer stack 2 to the "top" layer of the detector region. A reflective coating 12 is arranged on the side faces of the semiconductor layer stack 2 between the filler material 16 and the semiconductor layer stack.This increases the detection efficiency of the optoelectronic device 1, since light that has passed through the semiconductor layer stack 2 but has not yet been detected is reflected within the semiconductor layer stack 2, potentially to be detected "on a subsequent pass" when it passes through the semiconductor layer stack 2 again. The reflective coating 12 is also arranged along the side faces of the semiconductor layer stack in the emitter region 9. This enables directed emission of the light generated in the second active region 4b towards the light emission region 17 and more efficient extraction of the generated light by the light emission region 17.

[0065] Fig. Figure 8 shows an arrangement 20 according to some aspects of the proposed principle. The arrangement comprises a variety of optoelectronic devices 1, as shown in Fig. Figure 7 shows seven optoelectronic devices 1 arranged side-by-side on a common support substrate (not shown). In the illustrated embodiment, seven optoelectronic devices 1 are arranged on a common support substrate by way of example. For instance, several optoelectronic devices 1 can be arranged in rows and columns on the common support substrate. The common support substrate can, for example, be a CMOS wafer that provides the power supply circuitry required for operating the optoelectronic devices 1.

[0066] An exemplary procedure for manufacturing such an arrangement 20 may, for example, include the following steps: • Provision of the carrier substrate 13; • Providing the lower contact element 6; • Provision of semiconductor layer stack 2; • Structuring the semiconductor layer stack 2 to accommodate the emitter region (or regions) 9 and the detector region 10; • Providing a dielectric layer on the side faces of the semiconductor layer stack 2; • Providing the reflective coating 12 along the side faces of the semiconductor layer stack 2; • Providing the filling material 16; • Providing the central contact element 7 on the detector area 10; and • Positioning the upper contact element 8 on the emitter areas 9.

[0067] However, the aforementioned steps are to be understood as examples and may vary in their order and / or several steps may be omitted / are optional.

[0068] The Fig. 9A and Fig. Figure 9B shows steps of a method for operating an optoelectronic device according to some aspects of the proposed principle. Fig. Figure 9A shows the step of transmitting an optical signal from a first optoelectronic device 1a to a second optoelectronic device 1b, which receives the signal. The first optoelectronic device 1a is therefore subjected to a forward voltage V1 between the first and third layers 3a, 3c to emit light of a first wavelength. Simultaneously, the second optoelectronic device 1b is subjected to a reverse voltage V2, or a voltage of 0 V, between the first and third layers 3a, 3c to detect the light of the first wavelength. Fig. Figure 9B, on the other hand, shows the step of sending an optical signal from a second optoelectronic device 1b to the first optoelectronic device 1a, with the first optoelectronic device 1a receiving the signal. For this purpose, the second optoelectronic device 1b is subjected to a forward voltage V1 between the first and third layers 3a, 3c to emit light of a second wavelength. Simultaneously, the first optoelectronic device 1a is subjected to a reverse voltage V2 or a voltage of 0 V between the first and third layers 3a, 3c to detect the light of the second wavelength. The first and second wavelengths can be the same or different, depending on the optoelectronic devices.

[0069] Fig. Figure 10 shows a first embodiment of a system 30 for optical data transmission according to some aspects of the proposed principle. The system 30 comprises a first arrangement 20a of optoelectronic devices 1, a second arrangement 20b of optoelectronic devices 1, and a multicore fiber that optically couples the first and second arrangements. The optoelectronic devices 1 of the first arrangement 20a are optically coupled to a corresponding optoelectronic device 1 of the second arrangement 20b via an optical fiber 31 of the multicore fiber. Since the optoelectronic devices are configured to both emit and detect light of a desired wavelength, only one arrangement of optoelectronic devices is required on each side of the communicating objects, and the system 30 can provide bidirectional communication.

[0070] Fig.Figure 11 shows another view of a system 30 for optical data transmission according to some aspects of the proposed principle. In the system 30, a wavelength filter 14 is arranged at each of the detector regions 10 of the optoelectronic devices 1, which transmits at least the light emitted by the emitter region 9 of the respective optoelectronic device 1 of the opposite arrangement. REFERENCE MARK LIST 1 optoelectronic device 2 Semiconductor layer stacks 3a, 3b, 3c Semiconductor layer 4a, 4b active area 6 lower contact element 7 middle contact element 8 upper contact element 9 Emitter area 10 Detector area 11 column 12 reflective coating 13 Carrier substrate 14 filters 16 Filling material 17 Light emission area / Light incidence area 20, 20a, 20b order 30 System 31 fiber QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 113 465.5

[0001]

Claims

[1] Optoelectronic device (1), in particular a combined µ-LED and µ-detector, comprising a support substrate (13) and a semiconductor layer stack (2) arranged on the support substrate, wherein the semiconductor layer stack (2) comprises a first layer (3a), a second layer (3b), a third layer (3c), a first active region (4a) between the first and second layers (3a, 3b) and a second active region (4b) between the second and third layers (3b, 3c); wherein the first and second layers (3a, 3b) comprise a doping of a first conductivity type, wherein the second layer (3b) has a higher doping concentration than the first layer (3a); wherein the third layer (3c) comprises a doping of a second conductivity type that differs from the first conductivity type; and where the first active region (4a) has a smaller band gap than the second active region (4b). [2] Optoelectronic device according to claim 1, wherein the optoelectronic device (1) is configured to emit light when a forward voltage is applied between the first layer (3a) and the third layer (3c), and wherein the optoelectronic device (1) is configured to detect light when a voltage of 0 V or in the reverse direction is applied between the first layer (3a) and the third layer (3c). [3] Optoelectronic device according to claim 1 or 2, further comprising an upper contact element (8) in electrical contact with the third layer (3c) and a lower contact element (6) in electrical contact with the first layer (3a). [4] Optoelectronic device according to claim 3, wherein the upper or lower contact element (8, 6) is substantially transparent to light with an energy less than or equal to the band gap of the second active region (4b). [5] Optoelectronic device according to claim 3 or 4, wherein the upper contact element (8) comprises a first region and a second region spaced apart from each other on the third layer (3c) relative to the second active region (4b), or wherein the lower contact element (6) comprises a first region and a second region spaced apart from each other on the first layer (3a) relative to the first active region (4a). [6] Optoelectronic device according to any one of claims 1 to 5, wherein the upper contact element (8) comprises a reflective material layer covering the third layer (3c) opposite the second active area (4b), or wherein the lower contact element (6) comprises a reflective material layer covering the first layer (3a) opposite the first active area (4a). [7] Optoelectronic device according to any one of claims 1 to 6, wherein the semiconductor layer stack (2) comprises an emitter region (9) and a detector region (10), wherein the emitter region (9) comprises at least one region of the second active region (4b) and the third layer (3c) and wherein the detector region (10) comprises at least one region of the first layer (3a) and the first active region (4a). [8] Optoelectronic device according to claim 7, wherein in the detector area (10) the second active area (4b) and the third layer (3c) and optionally the second layer (3b) are removed. [9] Optoelectronic device according to claim 7, wherein in the emitter region (9) the first layer (3a) and the first active region (4a) and optionally the second layer (3b) are removed. [10] Optoelectronic device according to one of claims 7 to 9, wherein the emitter area (9) and the detector area (10) are spaced apart from each other by a slit (11). [11] Optoelectronic device according to any one of claims 7 to 10, further comprising a middle contact element (7) which is in electrical contact with the second layer (3b) and / or the first active area (4a) or the second active area (4b). [12] Optoelectronic device according to claim 11, wherein the middle contact element (7) is a Schottky contact element which is in electrical contact with the first active area (4a) or the second active area (4b). [13] Optoelectronic device according to any one of claims 1 to 12, further comprising a coupling structure on the upper contact element (8) opposite the carrier substrate (13) or on the lower contact element (8) opposite the carrier substrate (13) or on the middle contact element (8) opposite the carrier substrate (13). [14] Optoelectronic device according to any one of claims 1 to 13, further comprising an optical element on the upper contact element (8) opposite the support substrate (13) or on the lower contact element (6) opposite the support substrate (13) or on the middle contact element (7) opposite the support substrate (13), in particular a µ-lens or a photonic structure. [15] Optoelectronic device according to any one of claims 1 to 14, wherein the carrier substrate (13) comprises a supply circuit (14) which is in electrical contact with the upper and / or lower and / or middle contact element (6, 7, 8). [16] Arrangement (20) comprising a plurality of optoelectronic devices (1) according to any one of claims 1 to 15, arranged adjacent to each other on a common support substrate (13). [17] Arrangement according to claim 16, wherein the optoelectronic devices (1) are arranged in rows and columns. [18] Arrangement according to claim 16 or 17, wherein the optoelectronic devices (1) are optically isolated from each other. [19] System (30) for optical data transmission, comprising a first arrangement (20a) of optoelectronic devices (1) and a second arrangement (20b) of optoelectronic devices (1), wherein the optoelectronic devices (1) of the first arrangement (20a) are optically coupled to a corresponding optoelectronic device (1) of the second arrangement (20b) and wherein each optoelectronic device (1) of the first and second arrangement (20b) comprises an emitter and a detector area. [20] System according to claim 19, wherein the optoelectronic devices (1) of the first arrangement (20a) are configured to emit light of a first wavelength, and wherein the optoelectronic devices (1) of the second arrangement (20b) are configured to detect the light of the first wavelength emitted by the respective optoelectronic device (1) of the first arrangement (20a), and wherein the optoelectronic devices (1) of the second arrangement (20a) are configured to emit light of a second wavelength, and wherein the optoelectronic devices (1) of the first arrangement (20b) are configured to detect the light of the second wavelength emitted by the respective optoelectronic device (1) of the second arrangement (20a). [21] System according to claim 20, wherein the first and the second wavelength are different from each other. [22] System according to claim 21, wherein a first wavelength filter (14) is arranged above each detector area (10) of the optoelectronic devices (1) of the first arrangement (20a) and wherein a second wavelength filter (14) is arranged above each detector area (10) of the optoelectronic devices (1) of the second arrangement (20b), and wherein the first wavelength filter (14) is configured to transmit light of the second wavelength but blocks light of the first wavelength, and wherein the second wavelength filter (14) is configured to transmit light of the first wavelength but blocks light of the second wavelength. [23] System according to any one of claims 19 to 22, wherein at least one of the first and second arrangements (20a, 20b) is an arrangement according to any one of claims 16 to 18. [24] Method for operating an optoelectronic device (1) according to any one of claims 1 to 15, comprising the following steps: Applying a forward voltage (V1) between the third layer (3c) and the first or second layer (3a) to emit light of a first wavelength; Coupling of the light of the first wavelength from the optoelectronic device (1) through a light emission area (17) which is arranged on one side of the semiconductor layer stack (2) opposite the support substrate (13); Applying a voltage (V2) equal to 0V or in reverse direction between the first layer (3a) and the third or second layer (3c, 3b) to detect light of a second wavelength falling on a light incidence area (17) of the optoelectronic device (1) located on one side of the semiconductor layer stack (2) opposite the support substrate (13). [25] Method for operating a system (30) according to any one of claims 19 to 24, comprising the following steps: Emitting light of a first wavelength by means of a first optoelectronic device (1) of the first arrangement (20a); Coupling the light of the first wavelength into a first optical fiber (31); Transfer of the light of the first wavelength to a corresponding first optoelectronic device (1) of the second arrangement (20b); Coupling the light of the first wavelength into the first optoelectronic device (1) of the second arrangement (20b); and Detection of the light of the first wavelength by means of the first optoelectronic device (1) of the second arrangement (20b). [26] The method of claim 25, further comprising the following steps: Emitting light of a second wavelength by means of the first optoelectronic device (1) of the second arrangement (20b); Coupling of the light of the second wavelength into the first optical fiber (31); Transmission of the light of the second wavelength to the first optoelectronic device (1) of the first arrangement (20a); Coupling the light of the second wavelength into the first optoelectronic device (1) of the first arrangement (20a); and Detection of the light of the second wavelength by means of the first optoelectronic device (1) of the first arrangement (20a).

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