Semiconductor photodetector and preparation method thereof

Abstract

The present invention relates to the field of photoelectric detection technology, and provides a semiconductor photodetector and a preparation method thereof. The detector includes a functional layer, an absorption layer, a first doping layer, and a second doping layer. The absorption layer is located on a portion of the surface of the functional layer, and the absorption layer has a first side surface and a second side surface relative to each other; the first doping layer is located on the first side surface of the functional layer and the first side surface of the absorption layer; the second doping layer is located on the second side surface of the functional layer, the second side surface of the absorption layer, and the surface of the absorption layer away from the functional layer; the first doping layer and the second doping layer have a preset distance; the first doping layer and the second doping layer have different doping types. The semiconductor photodetector of the present invention adopts an "L"-shaped doping structure for the first doping layer and an "Y"-shaped doping structure for the second doping layer to form a P + and N + The ohmic contact region is used to optimize the carrier transport path and effectively shorten the carrier transit time, thereby increasing the operating bandwidth of the device and making it suitable for high-speed photoelectric detection applications.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and in particular to a semiconductor photoelectric detector and a preparation method thereof. Background Art

[0002] With the rapid development of information technology, a number of technologies, including artificial intelligence, optical computing, and big data, are undergoing rapid iteration, leading to an exponential increase in global data volumes. This poses unprecedented challenges to the real-time transmission capabilities, ultra-large-scale storage, and efficient computing capabilities of information systems. In this context, the performance of high-speed detectors, one of the core components of optoelectronic systems, is crucial for achieving efficient conversion of optical signals to electrical signals. In recent years, the development and innovation of silicon-based optoelectronics and heterogeneous integration technologies have laid the foundation for the large-scale application of high-speed detectors in areas such as data center optical interconnection, intelligent sensing networks, and telemedicine imaging. With the deep integration of optoelectronic fusion architectures and heterogeneous integration technologies, high-speed detectors will continue to empower the upgrade of information infrastructure in the intelligent era in more dimensions.

[0003] The bandwidth of high-speed detectors is primarily influenced by the RC constant and carrier transit time. Currently, for detectors with a horizontally propagated light field and left-right distributed electrodes, the carrier transit time of conventional doping structures is limited by the detector width. For such detectors with a fixed height, their width is affected by the operating wavelength and the material's refractive index. Therefore, for a fixed device size, reducing the carrier transit time can effectively increase the detector bandwidth. Summary of the Invention

[0004] The present invention provides a semiconductor photodetector and a preparation method thereof, which are used to solve the problem in the prior art that the bandwidth of a high-speed detector is affected by the width of the device in the left and right electrode structures. The detector structure can shorten the carrier transport time, thereby increasing the bandwidth of the detector to meet the growing data processing needs.

[0005] The present invention provides a semiconductor photodetector, comprising:

[0006] Functional layer;

[0007] an absorption layer, located on a portion of the surface of the functional layer, the absorption layer having a first side surface and a second side surface opposite to each other along a first direction;

[0008] a first doping layer, wherein a first side of the first doping layer is located on a first side surface of the functional layer, and a second side of the first doping layer is located on a first side surface of the absorption layer;

[0009] A second doping layer, wherein the middle portion of the second doping layer is located on the second side surface of the absorption layer, the first side of the second doping layer is located on the second side surface of the functional layer, and the second side of the second doping layer is located on the surface of the absorption layer away from the functional layer; an end of the first doping layer close to the second doping layer and an end of the second doping layer close to the first doping layer have a preset distance along the first direction; the first doping layer and the second doping layer have different doping types.

[0010] According to a semiconductor photodetector provided by the present invention, the first doped layer includes a first doped sub-region and a second doped sub-region connected to each other, the first doped sub-region is located on the first side surface of the functional layer, the second doped sub-region is located on the first side surface of the absorption layer, and the peak doping depth of the first doped sub-region is greater than the peak doping depth of the second doped sub-region.

[0011] According to a semiconductor photodetector provided by the present invention, the peak doping depth of the first doped sub-region is less than 200 nm, and / or the doping concentration of the first doped sub-region is 1×10 18 ~9×10 19 cm³.

[0012] According to a semiconductor photodetector provided by the present invention, the peak doping depth of the second doped sub-region is 20-100 nm, and / or the doping concentration of the second doped sub-region is 1×10 18 ~9×10 19 cm³.

[0013] According to a semiconductor photodetector provided by the present invention, the second doped layer includes a third doped sub-region, a fourth doped sub-region and a fifth doped sub-region connected in sequence;

[0014] The third doped sub-region is located on the second side surface of the functional layer, the fourth doped sub-region is located on the second side surface of the absorption layer, and the fifth doped sub-region is located on the surface of the absorption layer away from the functional layer. The peak doping depth of the third doped sub-region is greater than the peak doping depth of the fourth doped sub-region, and the peak doping depth of the third doped sub-region is greater than the peak doping depth of the fifth doped sub-region.

[0015] According to a semiconductor photodetector provided by the present invention, the peak doping depth of the second doping sub-region is equal to the peak doping depth of the fourth doping sub-region.

[0016] According to a semiconductor photodetector provided by the present invention, the thickness of the absorption layer is smaller than the width of the absorption layer.

[0017] According to a semiconductor photodetector provided by the present invention, the preset spacing is greater than 50 nm.

[0018] According to a semiconductor photodetector provided by the present invention, the functional layer comprises:

[0019] substrate;

[0020] a buffer layer, disposed on the substrate;

[0021] The absorption layer is arranged in a middle area of ​​a surface of the buffer layer facing away from the substrate, and a first side of the first doping layer and a first side of the second doping layer are located on a surface of the buffer layer.

[0022] According to a semiconductor photodetector provided by the present invention, the functional layer comprises:

[0023] substrate;

[0024] a buffer layer, disposed in a middle region of the substrate;

[0025] The absorption layer is arranged on a surface of the buffer layer facing away from the substrate, and the first side of the first doping layer and the first side of the second doping layer are both located on a side surface of the buffer layer and the surface of the substrate.

[0026] According to a semiconductor photodetector provided by the present invention, the functional layer includes a substrate, the absorption layer is arranged in the middle area of ​​the substrate, and the first side of the first doping layer and the first side of the second doping layer are located on the surface of the substrate.

[0027] The present invention also provides a method for preparing a semiconductor photodetector, comprising the following steps:

[0028] forming an absorption layer on a portion of the surface of the functional layer;

[0029] forming a first doping layer on the first side surface of the absorption layer and the first side surface of the functional layer;

[0030] A second doping layer is formed on the second side surface of the functional layer, the second side surface of the absorption layer, and the surface of the absorption layer away from the functional layer; an end of the first doping layer close to the second doping layer and an end of the second doping layer close to the first doping layer have a preset distance along the first direction; the first doping layer and the second doping layer have different doping types.

[0031] The semiconductor photodetector provided by the present invention adopts an "L"-shaped doping structure formed on the first side surface of the absorption layer and the first side surface of the functional layer by the first doping layer, and an "Y"-shaped doping structure formed on the second side surface of the functional layer, the second side surface of the absorption layer, and the surface of the absorption layer away from the functional layer by the second doping layer. + and N +The ohmic contact region is used to optimize the carrier transport path and effectively shorten the carrier transit time, thereby increasing the operating bandwidth of the device and making it suitable for high-speed photoelectric detection applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 It is a structural schematic diagram of the semiconductor photodetector provided by the present invention.

[0034] Figure 2 This is one of the structural schematic diagrams of the functional layer and the absorption layer provided by the present invention.

[0035] Figure 3 This is the second structural schematic diagram of the functional layer and the absorption layer provided by the present invention.

[0036] Figure 4 This is the third structural diagram of the functional layer and the absorption layer provided by the present invention.

[0037] Figure 5 It is a schematic flow chart of the method for preparing the semiconductor photodetector provided by the present invention.

[0038] Figure 6 It is a schematic diagram of the normalized response characteristics of a conventional doped Si waveguide evanescent wave coupled Ge photodetector and the photodetector of the present invention at different frequencies.

[0039] Reference numerals:

[0040] 100, functional layer; 110, substrate; 120, buffer layer; 101, first side surface; 102, second side surface;

[0041] 200, absorption layer; 210, first side surface; 220, second side surface; 230, upper surface of the absorption layer;

[0042] 300, first doped layer; 310, first doped sub-region; 320, second doped sub-region;

[0043] 400, second doped layer; 410, third doped sub-region; 420, fourth doped sub-region; 430, fifth doped sub-region;

[0044] 510, first electrode; 520, second electrode;

[0045] 600. Passivation layer. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0047] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0048] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0049] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0051] The following combination Figure 1-Figure 4 The semiconductor photodetector of the present invention is described.

[0052] An embodiment of the present invention provides a semiconductor photodetector, such as Figures 1 to 4 As shown, the semiconductor photodetector includes a functional layer 100 , an absorption layer 200 , a first doping layer 300 and a second doping layer 400 .

[0053] In which, the absorption layer 200 is located on a partial surface of the functional layer 100, and the absorption layer 200 has a first side surface 210 and a second side surface 220 opposite to each other along a first direction; the first doping layer 300 is located on the first side surface 210 of the absorption layer 200 and the first side surface 101 of the functional layer 100, and the second doping layer 400 is located on the second side surface 102 of the functional layer 100, the second side surface 220 of the absorption layer 200 and the surface of the absorption layer 200 away from the functional layer 100, and an end of the first doping layer 300 close to the second doping layer 400 and an end of the second doping layer 400 close to the first doping layer 300 have a preset distance L1 along the first direction; the first doping layer 300 and the second doping layer 400 have different doping types.

[0054] It is understood that the first direction is the width direction of the functional layer 100, the absorption layer 200 is located on a portion of the surface of the functional layer 100, and the first doping layer 300 and the second doping layer 400 are arranged on opposite sides of the absorption layer 200 along the first direction. Specifically, the first side of the first doping layer 300 is located on the first side surface 101 of the functional layer 100, and the second side of the first doping layer 300 is located on the first side surface 210 of the absorption layer 200. The middle portion of the second doping layer 400 is located on the second side surface 220 of the absorption layer 200, the first side of the second doping layer 400 is located on the second side surface 102 of the functional layer 100, and the second side of the second doping layer 400 is located on the surface of the absorption layer 200 away from the functional layer 100. It should be noted that the surface area of ​​the functional layer 100 in contact with the absorption layer 200 is the middle surface. Along the first direction, the surface areas of the functional layer 100 located on either side of the middle surface are the first side surface 101 and the second side surface 102, respectively.

[0055] Specifically, the first doping layer 300 adopts an "L"-shaped doping structure formed on the first side surface 210 of the absorption layer 200 and the first side surface 101 of the functional layer 100, and the second doping layer 400 adopts an "B"-shaped doping structure formed on the second side surface 102 of the functional layer 100, the second side surface of the absorption layer 200, and the absorption layer 200 away from the surface of the functional layer 100. In this way, the detector P + and N + The ohmic contact region utilizes "L" and "B"-shaped doping patterns, which spatially form interlaced yet isolated carrier fast channels, effectively shortening carrier transit time and thereby increasing the detector's bandwidth. It should be noted that the detector of this embodiment is particularly suitable for wide rectangular waveguide or wide ridge waveguide detectors, as well as infrared detectors requiring wide rectangular waveguides or wide ridge waveguides.

[0056] The semiconductor photodetector provided by the embodiment of the present invention adopts an "L"-shaped doping structure formed on the first side surface 210 of the absorption layer 200 and the first side surface 101 of the functional layer 100 by the first doping layer 300, and adopts an "Y"-shaped doping structure formed on the second side surface 102 of the functional layer 100, the second side surface of the absorption layer 200, and the surface of the absorption layer 200 away from the functional layer 100, to form a P + and N + The ohmic contact region is used to optimize the carrier transport path and effectively shorten the carrier transit time, thereby increasing the operating bandwidth of the device and making it suitable for high-speed photoelectric detection applications.

[0057] According to an embodiment of the present invention, the first doping layer 300 and the second doping layer 400 are doped with two materials of the detector, and the heavily doped region constituting the detector has P-type and N-type doping types.

[0058] For example, the heavily doped region of the detector is composed of a first doping layer 300 and a second doping layer 400, which are respectively doped with P-type and N-type (or vice versa). In specific implementation, there are two configurations of the heavily doped region of the detector:

[0059] In the first type, the first doping layer 300 is of P type and adopts an "L"-shaped structure; the second doping layer 400 is of N type and adopts an "B"-shaped structure.

[0060] In the second type, the first doping layer 300 is N-type and adopts an "L"-shaped structure, and the second doping layer 400 is P-type and adopts an "B"-shaped structure.

[0061] It should be noted that the "L"-shaped structure enables efficient lateral conductivity, while the "B"-shaped structure expands the longitudinal carrier collection range. The synergistic effect of the two significantly improves the detector's response speed and photoelectric conversion efficiency. Furthermore, the doping design covering the surface of the absorption layer 200, away from the functional layer 100, effectively avoids the risk of electrical short circuits, ensuring device stability under high-speed operating conditions.

[0062] In one embodiment of the present invention, Figure 1 As shown, the first doping layer 300 includes a first doping sub-region 310 and a second doping sub-region 320 connected to each other. The first doping sub-region 310 is located on the first side surface 101 of the functional layer 100 , and the second doping sub-region 320 is located on the first side surface 210 of the absorption layer 200 .

[0063] The second doped layer 400 includes a third doped sub-region 410, a fourth doped sub-region 420 and a fifth doped sub-region 430 connected in sequence; the third doped sub-region 410 is located on the second side surface 102 of the functional layer 100, the fourth doped sub-region 420 is located on the second side surface 220 of the absorption layer 200, and the fifth doped sub-region 430 is located on the surface of the absorption layer 200 away from the functional layer 100, that is, the fifth doped sub-region 430 is located on the upper surface 230 of the absorption layer.

[0064] Optionally, the second doped sub-region 320 and the fifth doped sub-region 430 have a preset distance L1 along the first direction, and the preset distance is greater than 50 nm.

[0065] It can be understood that the absorption layer 200 can be composed of GeSn or other semiconductor materials. The absorption layer 200 is also an active area for collecting carriers; the first doping layer 300 forms a first doping region, and the second doping layer 400 forms a second doping region. The doping of the second doping region on the upper surface of the active region is not connected to the first doping region, and a distance of more than 50 nm is maintained.

[0066] It should be noted that the maximum value of the preset interval L1 is determined according to the transmission wavelength and the transmission mode.

[0067] In one embodiment of the present invention, the peak doping depth of the first doping sub-region 310 is greater than the peak doping depth of the second doping sub-region 320 .

[0068] In one embodiment of the present invention, the peak doping depth of the third doping sub-region 410 is greater than the peak doping depth of the fourth doping sub-region 420 , and the peak doping depth of the third doping sub-region 410 is greater than the peak doping depth of the fifth doping sub-region 430 .

[0069] Optionally, the doping depth of the first doping sub-region 310 and the doping depth of the third doping sub-region 410 are substantially equal to form a good ohmic contact region. The peak doping depths of the second doping sub-region 320 and the fourth doping sub-region 420 are equal.

[0070] Furthermore, the peak doping depth of the fifth doping sub-region 430 is equal to the peak doping depth of the fourth doping sub-region 420 .

[0071] For example, the peak doping depth of the second doping sub-region 320, the peak doping depth of the fourth doping sub-region 420, and the peak doping depth of the fifth doping sub-region 430 are 20-100 nm, and the doping concentration is 1×10 18 ~9×10 19 cm³.

[0072] The peak doping depth of the first doping sub-region 310 and the peak doping depth of the third doping sub-region 410 are less than 200 nm, and the doping concentration is 1×10 18 ~9×10 19 cm³.

[0073] In this embodiment, the doping depth of the second doping sub-region 320 , the doping depth of the fourth doping sub-region 420 , and the doping depth of the fifth doping sub-region 430 are less than 50 nm.

[0074] The doping depth of the first doping sub-region 310 and the doping depth of the third doping sub-region 410 are less than 150 nm, and the peak doping concentration is 1×10 19 ~1×10 20 cm 3 .

[0075] It should be noted that the peak doping depth is the vertical distance from the surface where the doping concentration reaches its maximum during ion implantation or diffusion doping. This depth is determined by process parameters such as implantation energy and annealing conditions and represents the extreme point of the doping distribution. The doping depth is the effective boundary of the doped region, that is, the point where the doping concentration drops to the substrate background concentration or a specific threshold. In actual devices, the doping depth determines the location of the PN junction or the thickness of the conductive region.

[0076] It should be noted that the peak doping concentration is the maximum value of the concentration distribution curve of dopant atoms in the semiconductor material, that is, the highest doping concentration at a certain point in space. Doping concentration generally refers to the density of dopant atoms at a certain point or region in the material.

[0077] It is understood that both the first doping layer 300 and the second doping layer 400 form doped regions, with the ion concentration being highest at the surface or side of the doped region, and gradually decreasing from the surface to the interior or from the side to the interior. For example, the ion concentration of the first doping sub-region 310 gradually decreases from the surface toward the side closer to the functional layer 100; and the ion concentration of the second doping sub-region 320 gradually decreases from the side toward the side closer to the second doping layer 400.

[0078] In one embodiment of the present invention, the thickness of the absorption layer 200 is smaller than the width of the absorption layer 200 .

[0079] It is understandable that, during the detector preparation process, the thickness of the absorption layer 200 should be smaller than its width to ensure that the detector has a lower transmission loss within the working band.

[0080] The length direction of the absorption layer 200 is the direction of incident light transmission; the thickness direction of the absorption layer 200 is the direction perpendicular to the upper surface of the substrate, that is, Figure 1 The width direction of the absorption layer 200 is parallel to the upper surface of the substrate and perpendicular to the length direction (the direction of transmission of the incident light), that is, the first direction, Figure 1 The X direction in .

[0081] Specifically, an initial absorption layer is grown on the functional layer 100 and is etched to form an absorption layer 200, i.e., a light absorption region, on the functional layer 100. The etching height and width of the initial absorption layer are generally combined with the refractive index of the material and the working wavelength, and single-mode transmission of the light field in the working band is selected to achieve effective confinement of the light field within a specific wavelength range, thereby improving the performance and stability of the device.

[0082] It will be understood that the material forming the light absorption region of the detector may be formed by the substrate 110 and active materials on the substrate 110, including but not limited to SOI, Si, Ge, GeSn, GePb, InP, GaAs, GaN, GaSb, GaSb, InGaAs, InAs / GaSb and InAS / GaSb / AlSb superlattice, GaN, and Ga2O3 materials.

[0083] In a specific embodiment of the present invention, the functional layer 100 can take the following three forms.

[0084] The first one, such as Figure 2As shown, the functional layer 100 includes a substrate 110 and a buffer layer 120 disposed on the substrate 110 .

[0085] Specifically, the absorption layer 200 is disposed in the middle region of the surface of the buffer layer 120 facing away from the substrate 110 , and the first side of the first doping layer 300 and the first side of the second doping layer 400 are located on the surface of the buffer layer 120 .

[0086] It can be understood that a buffer layer 120 is grown on the surface of the substrate 110, an initial absorption layer is grown on the buffer layer 120, and the initial absorption layer is etched to form an absorption layer 200 in the middle area of ​​the buffer layer 120 along the first direction, and a first doping layer 300 and a second doping layer 400 are respectively formed on both sides of the absorption layer 200 along the first direction.

[0087] The buffer layer 120 and the absorption layer 200 both serve as active regions, with the buffer layer 120 serving as active region 1 and the absorption layer 200 serving as active region 2. Active region 2 is located on the central surface of active region 1. Ion implantation is used to perform ion heavy doping region implantation on one upper surface of active region 1 and one side surface of active region 2 to form a first doping layer 300, i.e., an "L"-shaped doping structure. Ion implantation is used to perform ion heavy doping region implantation on the other upper surface of active region 1, the other side surface of active region 2, and the upper surface of active region 2 to form a second doping layer 400, i.e., an "E"-shaped doping structure. It should be noted that when ion heavy doping region implantation is performed on the upper surface of active region 2, the upper surface of active region 2 cannot be completely covered, and should not be connected to the first doping layer 300, and a spacing of more than 50 nm should be maintained.

[0088] The second type, such as Figure 3 As shown, the functional layer 100 includes a substrate 110 and a buffer layer 120 disposed in a middle region of the substrate 110 .

[0089] Specifically, the absorption layer 200 is disposed on the surface of the buffer layer 120 facing away from the substrate 110 , and the first side of the first doping layer 300 and the first side of the second doping layer 400 are both located on the side of the buffer layer 120 and the surface of the substrate 110 .

[0090] It can be understood that an initial buffer layer is grown on the surface of the substrate 110, and the initial buffer layer is etched to form a buffer layer 120 in the middle area of ​​the substrate 110 along the first direction, and then an absorption layer 200 is grown on the buffer layer 120, and a first doping layer 300 and a second doping layer 400 are formed on both sides of the absorption layer 200 along the first direction.

[0091] The buffer layer 120 and the absorption layer 200 both serve as active areas, and ion implantation is performed on the upper surface of one side of the substrate 110 and on one side of the active area to form a first doped layer 300, that is, an "L"-shaped doping structure; and ion implantation is performed on the upper surface of the other side of the substrate 110, on the other side of the active area, and on the upper surface of the active area to form a second doped layer 400, that is, an "E"-shaped doping structure.

[0092] The third type, such as Figure 4 As shown, the functional layer 100 includes a substrate 110 .

[0093] Specifically, the absorption layer 200 is disposed in the middle region of the substrate 110 , and the first side of the first doping layer 300 and the first side of the second doping layer 400 are located on the surface of the substrate 110 .

[0094] It can be understood that an initial absorption layer is grown on the surface of the substrate 110 and is etched to form an absorption layer 200 in the middle area of ​​the substrate 110 along the first direction, and a first doping layer 300 and a second doping layer 400 are formed on both sides of the absorption layer 200 along the first direction.

[0095] The absorption layer 200 serves as an active area, and ion implantation is performed on the upper surface of one side of the substrate 110 and on one side of the active area to form a first doped layer 300, that is, an "L"-shaped doping structure; and ion implantation is performed on the upper surface of the other side of the substrate 110, on the other side of the active area, and on the upper surface of the active area to form a second doped layer 400, that is, an "E"-shaped doping structure.

[0096] It should be noted that the first doping layer 300 includes a first doping sub-region 310 and a second doping sub-region 320 that are connected, and the second doping layer 400 includes a third doping sub-region 410, a fourth doping sub-region 420 and a fifth doping sub-region 430 that are connected in sequence; wherein the first doping sub-region 310 and the third doping sub-region 410 are formed on the surface of the active region or the substrate, then the first doping sub-region 310 and the third doping sub-region 410 can also be formed by in-situ doping.

[0097] In a specific embodiment of the present invention, the buffer layer 120 and the absorption layer 200 are formed on the substrate 110 by homogeneous or heteroepitaxial growth, and heterogeneously bonded on the substrate 110 .

[0098] Optionally, semiconductor substrate 110 may be made of various materials, including InP, Si, Ge, SOI, GaAs, GaN, and GaSb. The material of absorption layer 200 may be formed from the substrate, or may be formed from epitaxial materials and heterojunctions. Examples of epitaxial and heterojunction materials include, but are not limited to, Si, Ge, GeSn, GePb, InP, GaAs, GaN, GaSb, GaSb, InGaAs, InAs / GaSb, InAs / GaSb / AlSb superlattices, GaN, and Ga2O3 materials.

[0099] In one embodiment of the present invention, Figure 1 As shown, the detector further includes counter electrodes, namely a first electrode 510 and a second electrode 520. The first electrode 510 is located on a first side of the first doped layer 300, and the second electrode 520 is located on a first side of the second doped layer 400. The first and second electrodes 510 and 520 are used to receive electrical excitation. Specifically, placing the first and second electrodes 510 and 520 on both sides of the absorption layer 200 can increase carrier transport speed, making it an ideal choice for manufacturing high-speed devices.

[0100] It should be noted that the first electrode 510 and the second electrode 520 may also be located on the substrate 110 on both sides of the absorption layer 200 .

[0101] Furthermore, insulating materials such as silicon oxide or silicon nitride are grown on the surfaces of the first doping layer 300 and the second doping layer 400 away from the functional layer 100, thereby forming a passivation layer 600 on the first doping layer 300 and the second doping layer 400, and openings are formed on the passivation layer 600 for the first electrode 510 and the second electrode 520 to expose the ohmic contact area of ​​the electrodes.

[0102] Based on the semiconductor photodetector provided in any of the above embodiments, an embodiment of the present invention provides a method for preparing a semiconductor photodetector, such as Figure 5 As shown, the preparation method comprises the following steps:

[0103] Step 10: forming an absorption layer 200 on a portion of the surface of the functional layer 100 .

[0104] Step 20 : forming a first doping layer 300 on the first side surface 210 of the absorption layer 200 and the first side surface 101 of the functional layer 100 .

[0105] Step 30 : forming a second doping layer 400 on the second side surface 102 of the functional layer 100 , the second side surface 220 of the absorption layer 200 , and the surface of the absorption layer 200 away from the functional layer 100 .

[0106] There is a preset distance between one end of the first doping layer 300 close to the second doping layer 400 and one end of the second doping layer 400 close to the first doping layer 300 along the first direction; the first doping layer 300 and the second doping layer 400 have different doping types.

[0107] It can be understood that the first doping layer 300 adopts an "L"-shaped doping structure formed on the first side surface 210 of the absorption layer 200 and the first side surface 101 of the functional layer 100, and the second doping layer 400 adopts an "B"-shaped doping structure formed on the second side surface 102 of the functional layer 100, the second side surface of the absorption layer 200, and the surface of the absorption layer 200 away from the functional layer 100. In this way, the detector P + and N + The ohmic contact region utilizes "L" and "B"-shaped doping patterns, which spatially form interlaced yet isolated carrier fast channels, effectively shortening carrier transit time and thereby increasing the detector's bandwidth. It should be noted that the detector of this embodiment offers the advantages of wide bandwidth and high responsivity, making it particularly suitable for wide rectangular waveguide or wide ridge waveguide detectors, as well as infrared detectors requiring such waveguides.

[0108] It should be noted that the structural types of the detector in this embodiment may include an evanescent wave coupling detector and a direct coupling detector.

[0109] In a specific embodiment of the present invention, Figure 1 As shown, when the functional layer 100 includes a substrate 110 and a buffer layer 120 disposed on the substrate 110, the method for preparing the semiconductor photodetector includes the following steps:

[0110] S1 . Growing a buffer layer 120 on the surface of the substrate 110 .

[0111] S2 . Growing an initial absorption layer on the buffer layer 120 and etching it.

[0112] It can be understood that an initial absorption layer is grown on the buffer layer 120, and the initial absorption layer is etched. The etching height and width are combined with the refractive index of the material and the working wavelength, and the single-mode transmission of the light field in the working band is selected, thereby forming a ridge-type absorption layer 200 in the middle area of ​​the buffer layer 120 along the first direction.

[0113] S3 , forming a first doping layer 300 .

[0114] It can be understood that the buffer layer 120 and the absorption layer 200 both serve as active areas, the buffer layer 120 serves as active area 1, and the absorption layer 200 serves as active area 2, and the active area 2 is located on the middle surface of the active area 1; ion implantation is used to perform ion heavy doping region implantation on one upper surface of the active area 1 and one side surface of the active area 2 to form a first doping layer 300, that is, an "L"-shaped doping structure.

[0115] S4. Forming a second doping layer 400.

[0116] It is understood that ion implantation is performed on the other upper surface of the active area 1, the other side surface of the active area 2, and the upper surface of the active area 2 to form a second doped layer 400, i.e., a "B"-shaped doped structure. It should be noted that when the ion implantation is performed on the upper surface of the active area 2, it should not be connected to the first doped layer 300 and a distance of more than 50 nm should be maintained.

[0117] S5. Forming a passivation layer 600.

[0118] It is understandable that insulating materials such as silicon oxide or silicon nitride are grown on the surfaces of the first doping layer 300 and the second doping layer 400 away from the functional layer 100, and holes are opened for the first electrode 510 and the second electrode 520, thereby forming a passivation layer 600 on the first doping layer 300 and the second doping layer 400.

[0119] In this embodiment, the first doping layer 300 and the second doping layer 400 are formed by ion implantation, and the ion implantation area is located outside the light field distribution. The doping depth of the upper surface and side surfaces of the active area 2 is less than 50nm; the doping depth of the upper surface of the active area 1 is less than 150nm, and the peak doping concentration is 1×10 19 ~1×10 20 cm 3 .

[0120] like Figure 6 As shown, the present invention compares the bandwidth performance of conventional doped Si waveguide evanescent wave coupled Ge photodetector with that of photodetector with "L" shape and "B" shape doping structure at -1V voltage; Figure 6 The horizontal axis represents frequency (Frequency), the unit is gigahertz (GHz); the vertical axis represents normalized response (Normalized response), the unit is decibel (dB). Figure 6Curve a represents a conventionally doped photodetector, while curve b represents the L-shaped and B-shaped photodetectors of this embodiment. It can be seen that the bandwidth of the photodetectors with the L-shaped and B-shaped doping structures of this embodiment reaches 50 GHz, while the bandwidth of detectors with conventional structures is only 27 GHz. This demonstrates that the doping structure proposed in this invention can significantly increase the operating bandwidth of photodetectors, making them more suitable for use in high-speed optical communication systems.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A semiconductor photodetector, characterized in that: include: Functional layer; an absorption layer, located on a portion of the surface of the functional layer, the absorption layer having a first side surface and a second side surface opposite to each other along a first direction; a first doping layer, wherein a first side of the first doping layer is located on a first side surface of the functional layer, and a second side of the first doping layer is located on a first side surface of the absorption layer; a second doping layer, wherein a middle portion of the second doping layer is located on a second side surface of the absorption layer, a first side of the second doping layer is located on a second side surface of the functional layer, and a second side of the second doping layer is located on a surface of the absorption layer away from the functional layer; an end of the first doping layer close to the second doping layer and an end of the second doping layer close to the first doping layer are spaced apart from each other along a first direction; and the first doping layer and the second doping layer have different doping types; The first doped layer includes a first doped sub-region and a second doped sub-region connected to each other, the first doped sub-region is located on a first side surface of the functional layer, and the second doped sub-region is located on a first side surface of the absorption layer; The second doping layer includes a third doping sub-region, a fourth doping sub-region and a fifth doping sub-region connected in sequence; the third doping sub-region is located on the second side surface of the functional layer, the fourth doping sub-region is located on the second side surface of the absorption layer, and the fifth doping sub-region is located on the surface of the absorption layer away from the functional layer. The peak doping depth of the third doping sub-region is greater than the peak doping depth of the fourth doping sub-region, and the peak doping depth of the third doping sub-region is greater than the peak doping depth of the fifth doping sub-region.

2. The semiconductor photodetector according to claim 1, wherein The peak doping depth of the first doping sub-region is greater than the peak doping depth of the second doping sub-region.

3. The semiconductor photodetector according to claim 2, wherein: The peak doping depth of the first doped sub-region is less than 200 nm, and / or the doping concentration of the first doped sub-region is 1×10 18 ~9×10 19 cm³; and / or, The peak doping depth of the second doped sub-region is 20-100 nm, and / or the doping concentration of the second doped sub-region is 1×10 18 ~9×10 19 cm³.

4. The semiconductor photodetector according to claim 1, wherein The peak doping depth of the second doping sub-region is equal to the peak doping depth of the fourth doping sub-region.

5. The semiconductor photodetector according to claim 1, wherein The thickness of the absorption layer is smaller than the width of the absorption layer, and / or The preset spacing is greater than 50 nm.

6. The semiconductor photodetector according to any one of claims 1 to 5, characterized in that: The functional layer includes: substrate; a buffer layer, disposed on the substrate; The absorption layer is arranged in a middle area of ​​a surface of the buffer layer facing away from the substrate, and a first side of the first doping layer and a first side of the second doping layer are located on a surface of the buffer layer.

7. The semiconductor photodetector according to any one of claims 1 to 5, characterized in that: The functional layer includes: substrate; a buffer layer, disposed in a middle region of the substrate; The absorption layer is arranged on a surface of the buffer layer facing away from the substrate, and the first side of the first doping layer and the first side of the second doping layer are both located on a side surface of the buffer layer and the surface of the substrate.

8. The semiconductor photodetector according to any one of claims 1 to 5, characterized in that: The functional layer includes a substrate, the absorption layer is arranged in a middle region of the substrate, and the first side of the first doping layer and the first side of the second doping layer are located on a surface of the substrate.

9. A method for preparing a semiconductor photodetector, characterized in that: include: forming an absorption layer on a portion of the surface of the functional layer; forming a first doping layer on the first side surface of the absorption layer and the first side surface of the functional layer; A second doping layer is formed on the second side surface of the functional layer, the second side surface of the absorption layer, and the surface of the absorption layer away from the functional layer; an end of the first doping layer close to the second doping layer and an end of the second doping layer close to the first doping layer are spaced apart from each other along a first direction; the first doping layer and the second doping layer have different doping types; The first doped layer includes a first doped sub-region and a second doped sub-region connected to each other, the first doped sub-region is located on a first side surface of the functional layer, and the second doped sub-region is located on a first side surface of the absorption layer; The second doping layer includes a third doping sub-region, a fourth doping sub-region and a fifth doping sub-region connected in sequence; the third doping sub-region is located on the second side surface of the functional layer, the fourth doping sub-region is located on the second side surface of the absorption layer, and the fifth doping sub-region is located on the surface of the absorption layer away from the functional layer. The peak doping depth of the third doping sub-region is greater than the peak doping depth of the fourth doping sub-region, and the peak doping depth of the third doping sub-region is greater than the peak doping depth of the fifth doping sub-region.

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