Infrared photoelectric detector and manufacturing method thereof

Abstract

The invention relates to the field of semiconductors, and discloses an infrared photoelectric detector and a manufacturing method thereof, and the method comprises the steps: growing a buffer layer on the upper surface of a substrate; etching the buffer layer to form a first super-structure grating; growing an epitaxial structure layer on the upper surface of the buffer layer; growing a top structure layer on the upper surface of the epitaxial structure layer; etching the top structure layer to form a second super-structure grating; the size of the grid bar in the second super-structure grating is different from that of the grid bar in the first super-structure grating; and manufacturing a first electrode on the upper surface of the second super-structure grating, and manufacturing a second electrode to obtain the infrared photoelectric detector. The first super-structure grating and the second super-structure grating which are asymmetric are manufactured, high light absorption and high quantum efficiency at a specific wavelength can be achieved through the guided mode resonance effect, the thickness of the epitaxial layer does not need to be increased, dark current can be effectively reduced, the ratio of the detector is increased, and the photoelectric performance of the infrared photoelectric detector is effectively improved; and meanwhile, the relatively high operation temperature of the infrared photoelectric detector is realized.

Description

Technical Field

[0001] The present application relates to the field of semiconductors, and in particular to an infrared photoelectric detector and a method for manufacturing the same. Background Art

[0002] Infrared photodetectors utilize the photoelectric effect of semiconductors for detection. When infrared light strikes the detector's photosensitive element, the photon's energy is absorbed by the photosensitive material, causing electrons in the material to transition from the valence band to the conduction band, generating electron-hole pairs. These electron-hole pairs, under the influence of an electric field, form an electric current, converting optical signals into electrical signals. However, current infrared photodetectors suffer from high dark current and low quantum efficiency, resulting in relatively poor photoelectric performance.

[0003] Therefore, how to solve the above technical problems should be the focus of those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide an infrared photodetector and a manufacturing method thereof, so as to improve the quantum efficiency of the infrared photodetector and reduce the dark current.

[0005] To solve the above technical problems, the present application provides a method for manufacturing an infrared photoelectric detector, comprising:

[0006] growing a buffer layer on the upper surface of the substrate;

[0007] Etching the buffer layer to form a first metagrating;

[0008] growing an epitaxial structure layer on the upper surface of the buffer layer;

[0009] growing a top structural layer on the upper surface of the epitaxial structural layer;

[0010] Etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating;

[0011] A first electrode is fabricated on the upper surface of the second metagrating, and a second electrode is fabricated to obtain an infrared photodetector.

[0012] As an implementation method, before growing the top structural layer on the upper surface of the epitaxial structural layer, the method further includes:

[0013] growing an intermediate structure layer on the upper surface of the epitaxial structure layer; wherein the refractive index of the intermediate structure layer is smaller than the refractive index of the top structure layer;

[0014] Growing a top structural layer on the upper surface of the epitaxial structural layer comprises:

[0015] A top structural layer is grown on the upper surface of the intermediate structural layer.

[0016] As an implementation method, etching the buffer layer to form the first metagrating includes:

[0017] The buffer layer is etched by dry etching to form a first metagrating.

[0018] As an implementation method, etching the buffer layer to form the first metagrating includes:

[0019] The buffer layer is etched by wet etching to form a first metagrating.

[0020] As an implementation method, etching the buffer layer by wet etching to form the first metagrating includes:

[0021] The buffer layer is etched with a citric acid aqueous solution to form a first metagrating, wherein the citric acid aqueous solution includes a citric acid aqueous solution, phosphoric acid and hydrogen peroxide, and the volume ratio of the citric acid aqueous solution: phosphoric acid: hydrogen peroxide is in the range of (1-10): (1-2):1.

[0022] As an implementation method, growing an epitaxial structure layer on the upper surface of the buffer layer includes:

[0023] growing an n-type doped contact layer on the upper surface of the buffer layer as a bottom contact layer;

[0024] growing an absorber layer on the upper surface of the bottom contact layer;

[0025] A p-type doped contact layer is grown on the upper surface of the absorption layer as a top contact layer.

[0026] As an implementation method, growing an epitaxial structure layer on the upper surface of the buffer layer includes:

[0027] growing a bottom contact layer on the upper surface of the buffer layer;

[0028] growing an electron barrier layer on the upper surface of the bottom contact layer;

[0029] growing an absorption layer on the upper surface of the electron barrier layer;

[0030] growing a hole barrier layer on the upper surface of the absorption layer;

[0031] A top contact layer is grown on the upper surface of the hole barrier layer.

[0032] As an implementation method, growing an epitaxial structure layer on the upper surface of the buffer layer includes:

[0033] growing a bottom contact layer on the upper surface of the buffer layer;

[0034] Growing a plurality of cascade structures on the upper surface of the bottom contact layer; each of the cascade structures comprises a stacked electron barrier layer, an absorption layer and a hole barrier layer;

[0035] A top contact layer is grown on the upper surface of the last of the cascade structures.

[0036] As an implementation method, the contrast of the second metagrating is greater than the contrast of the first metagrating, and the contrast of the first metagrating is zero.

[0037] The present application also provides an infrared photoelectric detector, which is manufactured using the manufacturing method of the infrared photoelectric detector described in any of the above embodiments.

[0038] The present application provides a method for manufacturing an infrared photodetector, comprising: growing a buffer layer on the upper surface of a substrate; etching the buffer layer to form a first metagrating; growing an epitaxial structure layer on the upper surface of the buffer layer; growing a top structure layer on the upper surface of the epitaxial structure layer; etching the top structure layer to form a second metagrating; the size of the gratings in the second metagrating is different from the size of the gratings in the first metagrating; and fabricating a first electrode on the upper surface of the second metagrating and a second electrode to obtain an infrared photodetector.

[0039] It can be seen that in the present application, when manufacturing the infrared photodetector, after growing a buffer layer on the substrate, the buffer layer is etched to form a first metagrating, then an epitaxial structure layer is grown on the buffer layer, and then a top structure layer is grown on the upper surface of the epitaxial structure layer, and the top structure layer is etched to form a second metagrating, and then a first electrode and a second electrode are grown. Because the grating sizes of the first metagrating and the second metagrating are different, the first metagrating and the second metagrating form an asymmetric grating structure, and then through the guided mode resonance effect, high light absorption and high quantum efficiency at a specific wavelength can be achieved. Without increasing the thickness of the epitaxial layer, dark current can be effectively reduced, the specific detector can be increased, and the photoelectric performance of the infrared photodetector can be effectively improved, while achieving a higher operating temperature of the infrared photodetector.

[0040] In addition, the present application also provides an infrared photoelectric detector having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] Figure 1 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 1 ;

[0043] Figure 2 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 2 ;

[0044] Figure 3 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 3 ;

[0045] Figure 4 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 4 ;

[0046] Figure 5 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 5 ;

[0047] Figure 6 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 6 ;

[0048] Figure 7 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 7 ;

[0049] Figure 8 The manufacturing method of an infrared photoelectric detector provided in the embodiment of the present application is as follows: Figure 8 ;

[0050] Figures 9 to 17 A flowchart of a manufacturing process of an infrared photoelectric detector provided in an embodiment of the present application;

[0051] In the figure, 1. substrate, 2. buffer layer, 21. first metagrating, 3. epitaxial layer, 31. n-type doped contact layer, 32. absorption layer, 33. p-type doped contact layer, 4. intermediate structure layer, 5. top structure layer, 51. second metagrating, 6. passivation layer, 7. first electrode, 8. second electrode. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present application.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0054] As mentioned in the background technology section, current infrared photodetectors have problems such as high dark current and low quantum efficiency, and the photoelectric performance of the photodetectors is relatively low.

[0055] In view of this, this application provides a method for manufacturing an infrared photoelectric detector, please refer to Figure 1 , the method may include:

[0056] Step S101: growing a buffer layer on the upper surface of the substrate.

[0057] It should be noted that the present application does not limit the growth method of the buffer layer, which can be set at will.

[0058] In one embodiment of the present application, the buffer layer may be grown by molecular beam epitaxy (MBE).

[0059] Using molecular beam epitaxy to grow the buffer layer can improve the crystallization quality of the buffer layer, significantly reduce lattice defects (such as dislocations, grain boundaries, etc.), reduce the recombination rate of photogenerated carriers, and increase carrier mobility, thereby improving the sensitivity and response speed of the infrared detector.

[0060] The materials of the substrate and the buffer layer are not limited in this application and can be selected at will. For example, the substrate material can be GaSb (gallium antimonide) and the buffer layer material can also be GaSb.

[0061] Step S102: etching the buffer layer to form a first metagrating.

[0062] The process of forming the first metagrating in this step includes: spin-coating photoresist on the upper surface of the buffer layer, then exposing, developing, and baking the photoresist, and etching the buffer layer using the photoresist as a mask.

[0063] It should be noted that the etching method of the buffer layer is not limited in this application.

[0064] A metagrating is a periodic or partially periodic array of subwavelength-scale gratings that diffracts incident light and independently controls each diffraction mode. Because the scatterer units in a metagrating do not require a continuous gradient of surface impedance, they are much simpler to manufacture. Furthermore, due to the larger unit size and limited number of diffraction orders, metagratings offer wider bandwidth and higher efficiency.

[0065] Step S103: growing an epitaxial structure layer on the upper surface of the buffer layer.

[0066] It should be pointed out that the specific structure of the epitaxial structure layer is not limited in this application and can be set at will.

[0067] Step S104: growing a top structural layer on the upper surface of the epitaxial structural layer.

[0068] The top structural layer is subsequently etched to form the second metagrating. It should be noted that the present application does not limit the growth method of the top structural layer and can be customized. For example, molecular beam epitaxy can be used for growth.

[0069] The material of the top structural layer can be gallium antimonide, etc., which is not limited in this application.

[0070] It should be noted that after the top structural layer is grown, the top structural layer and the epitaxial outer structural layer are further etched to form a device mesa, and the etching stops at the upper surface of the film layer in the epitaxial structural layer that is in direct contact with the buffer layer.

[0071] Step S105: etching the top structural layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0072] The size of the bars in the first metagrating is greater than the size of the bars in the second metagrating. The size of the bars refers to the width, and this application does not limit the specific sizes of the first metagrating and the second metagrating. The first metagrating and the second metagrating are respectively formed by a plurality of bars arranged at intervals.

[0073] In this application, the size of the grating bars in the first metagrating is different from the size of the grating bars in the second metagrating, so the first metagrating and the second metagrating form an asymmetric grating structure with two layers of upper and lower layers. Through the guided mode resonance effect, high light absorption and high quantum efficiency at specific wavelengths can be achieved without increasing the thickness of the epitaxial structure layer. It can effectively reduce dark current, increase the specific detector, effectively improve the photoelectric performance of the infrared detector, and achieve a higher operating temperature of the device.

[0074] In one embodiment of the present application, the contrast of the second metagrating is greater than the contrast of the first metagrating, and the contrast of the first metagrating is zero.

[0075] The contrast of the first metagrating is smaller than that of the second metagrating. A cavity can be formed between the first metagrating and the second metagrating. After light enters the cavity, it can be reflected back and forth multiple times to improve the absorption efficiency.

[0076] The first metagrating, with zero contrast at the bottom, exhibits broadband reflection properties and can serve as a bottom light reflector. The second metagrating, with high contrast at the top, exhibits resonance properties and strong light field confinement, effectively controlling light propagation and increasing absorption of target wavelengths. By constructing a double-layer grating, high light absorption and quantum efficiency at specific wavelengths can be achieved, effectively improving the optoelectronic performance of the Type II superlattice infrared detector.

[0077] Step S106: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0078] The first electrode is a metal electrode. This application does not limit the first electrode and can be configured arbitrarily. For example, the first electrode can include a stacked titanium (Ti) layer, a platinum (Pt) layer, and a gold (Au) layer. The thickness of the titanium layer can be 50 nm, the thickness of the platinum layer can be 50 nm, and the thickness of the gold layer can be 300 nm.

[0079] The first electrodes are located at the edge regions on both sides of the upper surface of the second metagrating.

[0080] The second electrode is a metal electrode. This application does not limit the second electrode and can be configured arbitrarily. For example, the second electrode can include a stacked titanium layer, a platinum layer, and a gold layer. The thickness of the titanium layer can be 50 nm, the thickness of the platinum layer can be 50 nm, and the thickness of the gold layer can be 300 nm.

[0081] It should be noted that the position of the second electrode is not limited in this application and can be set at will.

[0082] As an implementation method, the second electrode may be located on the upper surface of the device mesa.

[0083] As another possible implementation method, the second electrode may also be located on the lower surface of the substrate. The substrate is thinned, and then the second electrode is deposited on the lower surface of the substrate.

[0084] After the first electrode and the second electrode are deposited, annealing is performed to achieve ohmic contact between the first electrode and the top structure layer, and between the second electrode and the film layer in the epitaxial structure layer that is in direct contact with the buffer layer.

[0085] In this embodiment, when fabricating an infrared photodetector, after growing a buffer layer on a substrate, the buffer layer is etched to form a first metagrating. An epitaxial structure layer is then grown on the buffer layer. A top structure layer is then grown on the upper surface of the epitaxial structure layer, and the top structure layer is etched to form a second metagrating. Finally, a first electrode and a second electrode are grown. Because the gratings of the first and second metagratings differ in size, they form an asymmetric grating structure. This, through the guided mode resonance effect, enables high light absorption and high quantum efficiency at specific wavelengths. Without increasing the thickness of the epitaxial layer, this effectively reduces dark current, increases the specific photodetector, and improves the photoelectric performance of the infrared photodetector, while also enabling a higher operating temperature.

[0086] Please refer to Figure 2 Based on the above embodiment, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0087] Step S201: growing a buffer layer on the upper surface of the substrate.

[0088] Step S202: etching the buffer layer to form a first metagrating.

[0089] Step S203: growing an epitaxial structure layer on the upper surface of the buffer layer.

[0090] Step S204: growing an intermediate structure layer on the upper surface of the epitaxial structure layer; the refractive index of the intermediate structure layer is smaller than the refractive index of the top structure layer.

[0091] It should be noted that the present application does not limit the growth method of the intermediate structure layer, which can be set at will. For example, molecular beam epitaxy can be used for growth.

[0092] The material of the intermediate structure layer is not limited in this application, as long as the refractive index is lower than that of the top structure layer. For example, when the material of the top structure layer is gallium antimonide (GaSb), the material of the intermediate structure layer can be aluminum arsenide antimony (AlAsSb).

[0093] Step S205: growing a top structural layer on the upper surface of the middle structural layer.

[0094] Step S206: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0095] Step S207: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0096] It should be noted that, for step S201 , step S202 , step S203 , step S205 , step S206 and step S207 , reference may be made to the contents of the above embodiment and will not be described in detail here.

[0097] In this embodiment, an intermediate structure layer is grown between the epitaxial structure layer and the top structure layer. The refractive index of the intermediate structure layer is smaller than that of the top structure layer. The intermediate structure layer has a filtering effect, which can enable the infrared photodetector to selectively transmit infrared light of a specific wavelength, thereby optimizing the response characteristics of the infrared photodetector.

[0098] Please refer to Figure 3 Based on any of the above embodiments, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0099] Step S301: growing a buffer layer on the upper surface of the substrate.

[0100] Step S302: etching the buffer layer using a dry etching method to form a first metagrating.

[0101] The present application does not specifically limit the dry etching method of the buffer layer, and the method can be selected by the user. For example, inductively coupled plasma (ICP) etching or reactive ion etching (RIE) can be used.

[0102] When inductively coupled plasma etching is used, BCl3 gas can be selected as the etching gas, and Ar gas is an inert gas.

[0103] Step S303: growing an epitaxial structure layer on the upper surface of the buffer layer.

[0104] Step S304: growing an intermediate structure layer on the upper surface of the epitaxial structure layer; the refractive index of the intermediate structure layer is smaller than the refractive index of the top structure layer.

[0105] Step S305: growing a top structural layer on the upper surface of the middle structural layer.

[0106] Step S306: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0107] Step S307: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0108] It should be noted that, for step S301 , step S303 , step S304 , step S305 , step S306 and step S307 , reference may be made to the contents of the above embodiment and will not be described in detail here.

[0109] In this embodiment, the buffer layer is etched by dry etching to form the first metagrating. Dry etching has the advantages of high speed and high etching precision, and can improve the production efficiency of infrared photodetectors.

[0110] Please refer to Figure 4 Based on the above embodiment, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0111] Step S401: growing a buffer layer on the upper surface of the substrate.

[0112] Step S402: etching the buffer layer using a wet etching method to form a first metagrating.

[0113] It should be pointed out that the present application does not limit the corrosive liquid used for wet etching, as long as it can achieve the etching effect.

[0114] As an implementation method, etching the buffer layer by wet etching to form the first metagrating includes:

[0115] A buffer layer is etched with a citric acid aqueous solution to form a first metagrating, wherein the citric acid aqueous solution includes a citric acid aqueous solution, phosphoric acid and hydrogen peroxide, and the volume ratio of the citric acid aqueous solution: phosphoric acid: hydrogen peroxide is in the range of (1-10): (1-2):1.

[0116] For example, the volume ratio of citric acid aqueous solution: phosphoric acid: hydrogen peroxide can be 10:1:1, 8:1:1, 8:2:1, 6:1:1, 4:1:1, etc.

[0117] Step S403: growing an epitaxial structure layer on the upper surface of the buffer layer.

[0118] Step S404: growing an intermediate structure layer on the upper surface of the epitaxial structure layer; the refractive index of the intermediate structure layer is smaller than the refractive index of the top structure layer.

[0119] Step S405: growing a top structural layer on the upper surface of the middle structural layer.

[0120] Step S406: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0121] Step S407: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0122] It should be noted that, for step S401 , step S403 , step S404 , step S405 , step S406 and step S407 , reference may be made to the contents of the above embodiment and will not be described in detail here.

[0123] In this embodiment, the buffer layer is etched by wet etching to form the first metagrating. The wet etching method has the characteristics of low cost, high uniformity, and easy operation, thereby reducing the production cost of infrared photodetectors and improving quality.

[0124] Please refer to Figure 5 Based on any of the above embodiments, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0125] Step S501: growing a buffer layer on the upper surface of the substrate.

[0126] Step S502: etching the buffer layer to form a first metagrating.

[0127] Step S503: growing an n-type doped contact layer on the upper surface of the buffer layer as a bottom contact layer.

[0128] Step S504: growing an absorption layer on the upper surface of the bottom contact layer.

[0129] Step S505: growing a p-type doped contact layer on the upper surface of the absorption layer as a top contact layer to form an epitaxial structure layer.

[0130] The bottom contact layer can be an n-type doped type II superlattice material bottom contact layer, and the doping concentration in the n-type doped type II superlattice material bottom contact layer is about 10 18 cm −3 The absorption layer can be a non-intentionally doped type II superlattice material absorption layer, and the top contact layer can be a p-type type II superlattice material top contact layer, and the doping concentration in the p-type type II superlattice material top contact layer is about 10 18 cm −3 .

[0131] It should be pointed out that the present application does not limit the type of type II superlattice material and it can be selected at will.

[0132] For example, the type II superlattice material may be InAs / GaSb, InAs / InAsSb or other antimonide type II superlattice materials, which are not specifically limited in this application.

[0133] Type II superlattice materials have the advantages of large effective mass, suppressed Auger recombination, adjustable band gap and wide wavelength coverage range. The epitaxial structure layer uses type II superlattice materials to improve the photoelectric performance of infrared photodetectors.

[0134] Since the infrared photodetector in this application is made with an asymmetric metagrating structure, the dark current can be effectively reduced without increasing the thickness of the absorption layer in the epitaxial structure layer, the specific detector can be increased, and the photoelectric performance of the infrared photodetector can be effectively improved, while achieving a higher operating temperature of the infrared photodetector.

[0135] In this embodiment, the bottom contact layer is an n-type doped contact layer, and the top contact layer is a p-type doped contact layer, that is, the epitaxial structure layer is a PIN structure. However, the structure of the epitaxial structure layer is not limited in this application. In other embodiments of this application, forming the epitaxial structure layer on the upper surface of the buffer layer includes:

[0136] growing an n-type doped layer on the upper surface of the buffer layer as a bottom contact layer;

[0137] growing a barrier layer on the upper surface of the bottom contact layer;

[0138] An n-type doped layer is grown on the upper surface of the absorption layer as a top contact layer.

[0139] In this embodiment, the epitaxial structure layer adopts an nBn (n-Barrier-n, n-type doping layer-barrier layer-n-type doping layer) structure.

[0140] In other embodiments of the present application, forming an epitaxial structure layer on the upper surface of the buffer layer includes:

[0141] growing a p-type doped layer on the upper surface of the buffer layer as a bottom contact layer;

[0142] growing a barrier layer on the upper surface of the bottom contact layer;

[0143] A p-type doped layer is grown on the upper surface of the absorption layer as a top contact layer.

[0144] In this embodiment, the epitaxial structure layer adopts a pBp (p-Barrier-p, p-type doped layer-barrier layer-p-type doped layer) structure.

[0145] Step S506: growing a top structural layer on the upper surface of the epitaxial structural layer.

[0146] Step S507: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0147] Step S508: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0148] Please refer to Figure 6Based on the above embodiment, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0149] Step S601: growing a buffer layer on the upper surface of the substrate.

[0150] Step S602: etching the buffer layer to form a first metagrating.

[0151] Step S603: growing a bottom contact layer on the upper surface of the buffer layer.

[0152] Step S604: growing an electron barrier layer on the upper surface of the bottom contact layer.

[0153] Step S605: growing an absorption layer on the upper surface of the electron barrier layer.

[0154] Step S606: growing a hole barrier layer on the upper surface of the absorption layer.

[0155] Step S607: growing a top contact layer on the upper surface of the hole barrier layer to form an epitaxial structure layer.

[0156] In this embodiment, the epitaxial structure layer includes a bottom contact layer, an electron barrier layer, an absorption layer, a hole barrier layer and a top contact layer. That is, the infrared photodetector type in this embodiment is CBIRD (Complementary Barrier Infrared Detector), which can further reduce the dark current, so that the photodetector can maintain high performance even at room temperature; and enable the photodetector to cover a wider infrared band and expand the scope of application.

[0157] Step S608: growing a top structural layer on the upper surface of the epitaxial structural layer.

[0158] Step S609: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0159] Step S610: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0160] Please refer to Figure 7 Based on the above embodiment, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0161] Step S701: growing a buffer layer on the upper surface of the substrate.

[0162] Step S702: etching the buffer layer to form a first metagrating.

[0163] Step S703: growing a bottom contact layer on the upper surface of the buffer layer.

[0164] Step S704: growing a plurality of cascade structures on the upper surface of the bottom contact layer; each cascade structure includes a stacked electron barrier layer, an absorption layer, and a hole barrier layer.

[0165] The number of cascade structures is at least two. It should be noted that the specific number of cascade structures is not limited in this application and depends on the circumstances.

[0166] In this embodiment, the epitaxial structure includes a bottom contact layer, multiple cascade structures, and a top contact layer. This means the infrared photodetector in this embodiment is an ICIP (interband cascade infrared photodetector). ICIPs employ a multi-stage short absorption region structure, which reduces recombination of photogenerated carriers and improves the detector's detectivity at high operating temperatures. This structure enables the detector to maintain high quantum efficiency even at high temperatures, avoiding the decrease in responsivity caused by a shortened diffusion length.

[0167] It should be pointed out that the present application does not limit the growth method of the epitaxial structure layer, which can be set at will.

[0168] In one embodiment of the present application, molecular beam epitaxy can be used to grow each film layer in the epitaxial structure layer to improve the crystallization quality of the film layer in the epitaxial structure layer and improve the performance of the infrared photodetector.

[0169] Step S705: growing a top contact layer on the upper surface of the last cascade structure to form an epitaxial structure layer.

[0170] Step S706: growing a top structural layer on the upper surface of the epitaxial structural layer.

[0171] Step S707: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0172] Step S708: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0173] Based on any of the above embodiments, in one embodiment of the present application, after etching the top contact layer to form the second metagrating, the method may further include:

[0174] growing a passivation layer on the surface of the epitaxial structure layer;

[0175] At least the passivation layer located on the top contact layer is removed.

[0176] It should be noted that the material of the passivation layer is not limited in this application and can be set at will. For example, the material of the passivation layer can be silicon dioxide.

[0177] The passivation layer can be removed using photolithography and etching. When the second electrode is located on the device mesa, the passivation layer located on the device mesa and the passivation layer on the upper surface of the top structural layer where the second electrode will be grown need to be removed. When the second electrode is located on the lower surface of the substrate, only the passivation layer located on the upper surface of the top structural layer needs to be removed.

[0178] In this embodiment, a passivation layer is provided for protection, thereby reducing the surface leakage current of the photodetector.

[0179] Please refer to Figure 8 Based on any of the above embodiments, in one embodiment of the present application, a method for manufacturing an infrared photoelectric detector includes:

[0180] Step S801: growing a buffer layer on the upper surface of the substrate.

[0181] Step S802: etching the buffer layer to form a first metagrating.

[0182] Step S803: growing an epitaxial structure layer on the upper surface of the buffer layer.

[0183] Step S804: growing a top structural layer on the upper surface of the epitaxial structural layer.

[0184] Step S805: etching the top structure layer to form a second metagrating; the size of the grating strips in the second metagrating is different from the size of the grating strips in the first metagrating.

[0185] Step S806: fabricating metal nanoparticles on the upper surface of the second metagrating.

[0186] It should be noted that the position of the metal nanoparticles is not limited in this embodiment. For example, the metal nanoparticles can be located on the surface of the bars of the second metagrating, or on the spaced surfaces between the bars of the second metagrating.

[0187] It should be noted that the metal particles are not limited in this application and can be selected at will. For example, the metal particles can be any one of gold particles, platinum particles, and silver particles, or any combination thereof.

[0188] Step S807: fabricating a first electrode and a second electrode on the upper surface of the second metagrating to obtain an infrared photodetector.

[0189] In this embodiment, metal nanoparticles are produced on the surface of the second metagrating. The metal nanoparticles contain a large number of free electrons. The nanoparticles couple with the incident light to produce localized surface plasmon resonance, so that the light is captured on the surface around the metal nanoparticles, thereby enhancing the light absorption and photoelectric conversion efficiency of the adjacent materials.

[0190] The following describes the manufacturing process of the infrared photoelectric detector in this application using a specific case.

[0191] Step 1: Figure 9 As shown, a buffer layer 2 is grown on the upper surface of the cleaned substrate 1 by molecular beam epitaxy. The material of the buffer layer 22 may be GaSb.

[0192] Step 2: Figure 10 As shown, the substrate 1 on which the buffer layer 2 is deposited is cleaned with an organic solvent, blown dry, and then pre-treated. Then, a photoresist is spin-coated on the upper surface of the buffer layer 2 using a coater. After the coater is coated, a pre-bake process is performed. Then, a photomask is used to place the coated substrate 1 on a sample stage and push it into a photolithography machine for exposure. After exposure, a developer is used for development. After development, a post-bake process is performed. The buffer layer 2 is wet-etched using the photoresist as a mask. The ratio of citric acid aqueous solution: phosphoric acid: hydrogen peroxide in the etching solution used is 10:1:1. The etching time is controlled according to the table etching rate to form a first metagrating 21.

[0193] Step 3: Figure 11 As shown, a bottom contact layer 31 of an n-type doped type II superlattice material, an absorption layer 32 of an unintentionally doped type II superlattice material, a top contact layer 33 of a p-type type II superlattice material, an intermediate structure layer 4, and a top structure layer 5 are sequentially epitaxially grown on an epitaxial wafer having a first metagrating 21 by molecular beam epitaxy. The refractive index of the intermediate structure layer 4 is smaller than that of the top structure layer 5. The bottom contact layer 31 of the n-type doped type II superlattice material, the absorption layer 32 of the unintentionally doped type II superlattice material, and the top contact layer 33 of the p-type type II superlattice material form an epitaxial structure layer 3. The material of the intermediate structure layer 4 is AlAsSb, and the material of the top structure layer 5 is GaSb.

[0194] Step 4: Figure 12 As shown, the epitaxial wafer is cleaned and dried, and then the device mesa is etched by spin coating photoresist, ultraviolet lithography, and etching, and the etching stops at the upper surface of the bottom contact layer of the n-type doped type II superlattice material;

[0195] Step 5: Figure 13As shown, a passivation layer 6 is grown on the entire upper surface by using ICP-CVD (Inductively Coupled Plasma-Chemical Vapor Deposition). The material of the passivation layer 6 is silicon dioxide and has a thickness of 300 nm.

[0196] Step 6: Figure 14 As shown, a passivation layer 6 is grown on the surface of the epitaxial wafer. Before the coating, an adhesive is applied first, followed by a spin coating. After the coating, a pre-baking process is performed. After the pre-baking process is completed, a photolithography exposure process is performed. Then, a development process is performed. After the development process is completed, a post-baking process and a coating process are performed. Finally, a window is etched on the passivation layer 6 using a wet etching method. The etching solution can be a hydrofluoric acid aqueous solution with a ratio of hydrofluoric acid to water of 1:10.

[0197] Step 7: Figure 15 and Figure 16 As shown, the epitaxial wafer is stripped and cleaned, and then the surface of the top structural layer 5 is coated with glue and pre-baked. After the plate is aligned with the photomask, the exposure mode is adjusted to perform exposure and development. After development, no post-baking is required, and the glue treatment is performed. Then, the top structural layer 5 is etched to obtain the second metagrating 51. The grating width of the second metagrating 51 is several hundred nanometers, and the width of the grating interval is several tens of nanometers.

[0198] Step 8: Figure 17 As shown, a metal layer is sputtered using magnetron sputtering, and the metal layer includes a Ti layer, a Pt layer, and an Au layer stacked in sequence, with thicknesses of 50 nm, 50 nm, and 300 nm, respectively; the metal layer covers the entire epitaxial wafer, and then the metal layer that is not an electrode portion is stripped off to form a first electrode 7 and a second electrode 8; wherein, the metal layer is stripped off by soaking in acetone to dissolve the photoresist under the metal layer, thereby achieving metal stripping;

[0199] Step 9: annealing the epitaxial wafer to achieve ohmic contact between the electrode and the contact layer to obtain an infrared photodetector.

[0200] The present application also provides an infrared photoelectric detector, which is manufactured using the manufacturing method of the infrared photoelectric detector of any of the above embodiments.

[0201] like Figure 16 and Figure 17 As shown, the infrared photodetector includes a substrate 1, a buffer layer 2, an epitaxial layer 3, a top structure layer 5, a first electrode 7 and a second electrode 8, wherein the upper surface of the buffer layer 2 is provided with a first metagrating 21, and the upper surface of the top structure layer 5 is provided with a second metagrating 51, and the size W1 of the grating in the first metagrating 21 is greater than the size W2 of the grating in the second metagrating 51.

[0202] Among them, the epitaxial layer may include an n-type doped contact layer 31, an absorption layer 32 and a p-type doped contact layer 33; or, include an n-type doped layer, a barrier layer and an n-type doped layer, or, include a p-type doped layer, a barrier layer and a p-type doped layer, or, include a bottom contact layer, an electron barrier layer, an absorption layer, a hole barrier layer and a top contact layer, or include a bottom contact layer, multiple cascade structures and a top contact layer, each cascade structure including a stacked electron barrier layer, an absorption layer and a hole barrier layer.

[0203] In the infrared photodetector of this embodiment, the first metagrating 21 and the second metagrating 51 form an asymmetric grating structure with two layers, which can achieve high light absorption and high quantum efficiency at specific wavelengths through the guided mode resonance effect. There is no need to increase the thickness of the absorption layer 32 in the epitaxial structure layer, which can effectively reduce dark current, increase the specific detector, effectively improve the photoelectric performance of the infrared detector, and achieve a higher operating temperature of the device.

[0204] As an implementation method, the infrared photodetector may further include an intermediate structural layer 4 having a refractive index smaller than that of the top structural layer 5. The intermediate structural layer 4 has a filtering effect, which enables the infrared photodetector to selectively transmit infrared light of a specific wavelength, thereby optimizing the response characteristics of the infrared photodetector.

[0205] As an implementation method, the infrared photodetector may further include a passivation layer 6 to reduce surface leakage current.

[0206] As an implementation method, the infrared photodetector may further include metal nanoparticles arranged on the surface of the second metagrating 51. The metal nanoparticles contain a large number of free electrons. The nanoparticles couple with the incident light to produce localized surface plasmon resonance, so that the light is captured on the surface around the metal nanoparticles, thereby enhancing the light absorption and photoelectric conversion efficiency of the adjacent materials.

[0207] The present application also provides an electronic device, which includes the infrared photodetector of the above embodiment.

[0208] The type of electronic device is not limited in this application. For example, the electronic device may be an infrared imaging device, a free-space optical communication device, a frequency comb spectrometer, etc.

[0209] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0210] The infrared photoelectric detector and its manufacturing method provided by this application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of this application.

Claims

1. A method for manufacturing an infrared photoelectric detector, characterized in that: include: growing a buffer layer on the upper surface of the substrate; Etching the buffer layer to form a first metagrating; growing an epitaxial structure layer on the upper surface of the buffer layer; growing a top structural layer on the upper surface of the epitaxial structural layer; Etching the top structural layer to form a second metagrating; The size of the bars in the second metagrating is different from the size of the bars in the first metagrating; A first electrode is fabricated on the upper surface of the second metagrating, and a second electrode is fabricated to obtain an infrared photodetector.

2. The method for manufacturing an infrared photodetector according to claim 1, wherein: Before growing the top structural layer on the upper surface of the epitaxial structural layer, the method further comprises: growing an intermediate structure layer on the upper surface of the epitaxial structure layer; wherein the refractive index of the intermediate structure layer is smaller than the refractive index of the top structure layer; Growing a top structural layer on the upper surface of the epitaxial structural layer comprises: A top structural layer is grown on the upper surface of the intermediate structural layer.

3. The method for manufacturing an infrared photodetector according to claim 1, wherein: Etching the buffer layer to form a first metagrating includes: The buffer layer is etched by dry etching to form a first metagrating.

4. The method for manufacturing an infrared photodetector according to claim 1, wherein: Etching the buffer layer to form a first metagrating includes: The buffer layer is etched by wet etching to form a first metagrating.

5. The method for manufacturing an infrared photodetector according to claim 4, wherein: Etching the buffer layer by wet etching to form a first metagrating includes: The buffer layer is etched with a citric acid aqueous solution to form a first metagrating, wherein the citric acid aqueous solution includes a citric acid aqueous solution, phosphoric acid and hydrogen peroxide, and the volume ratio of the citric acid aqueous solution: phosphoric acid: hydrogen peroxide is in the range of (1-10): (1-2):

1.

6. The method for manufacturing an infrared photodetector according to claim 1, wherein: Growing an epitaxial structure layer on the upper surface of the buffer layer comprises: growing an n-type doped contact layer on the upper surface of the buffer layer as a bottom contact layer; growing an absorber layer on the upper surface of the bottom contact layer; A p-type doped contact layer is grown on the upper surface of the absorption layer as a top contact layer.

7. The method for manufacturing an infrared photodetector according to claim 1, wherein: Growing an epitaxial structure layer on the upper surface of the buffer layer comprises: growing a bottom contact layer on the upper surface of the buffer layer; growing an electron barrier layer on the upper surface of the bottom contact layer; growing an absorption layer on the upper surface of the electron barrier layer; growing a hole barrier layer on the upper surface of the absorption layer; A top contact layer is grown on the upper surface of the hole barrier layer.

8. The method for manufacturing an infrared photodetector according to claim 1, wherein: Growing an epitaxial structure layer on the upper surface of the buffer layer includes: growing a bottom contact layer on the upper surface of the buffer layer; Growing a plurality of cascade structures on the upper surface of the bottom contact layer; each of the cascade structures comprises a stacked electron barrier layer, an absorption layer and a hole barrier layer; A top contact layer is grown on the upper surface of the last of the cascade structures.

9. The method for manufacturing an infrared photodetector according to any one of claims 1 to 8, wherein: The contrast of the second metagrating is greater than the contrast of the first metagrating, and the contrast of the first metagrating is zero.

10. An infrared photoelectric detector, characterized in that: The infrared photoelectric detector is manufactured using the manufacturing method of the infrared photoelectric detector according to any one of claims 1 to 9.

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