Photoelectric detector and preparation method thereof

Abstract

The invention provides a photoelectric detector and a preparation method thereof, the photoelectric detector comprises a semiconductor substrate, a photoelectric detection layer, a first electrode and a second electrode, the photoelectric detection layer is located on the semiconductor substrate and comprises a two-dimensional semiconductor photoelectric detection layer and an organic photoelectric detection layer which are stacked, the first electrode and the second electrode are arranged in the photoelectric detection layer or on the photoelectric detection layer in a spaced mode, the first electrode and the second electrode are made of different materials and form asymmetric source and drain electrodes, the barrier height is reduced, dark current is reduced, light current is improved, and the photoelectric detection efficiency is improved. Therefore, the current switching ratio, the responsivity and the field effect mobility of the device are improved, and the turn-on voltage of the device is reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a photodetector and a method for preparing the same. Background Art

[0002] Organic photoresponsive organic field effect transistor (PhOFET) has attracted widespread attention due to its simple preparation process, low cost, light weight and flexibility of the prepared products. PhOFET is a type of organic photodetector. Compared with organic photodiode (OPD), which is also a member of the organic photodetector family, PhOFET integrates the detection and amplification functions of light signals, and has higher sensitivity and lower noise. Since PhOFET has a smaller effective photosensitive area (channel area), this type of device can usually obtain photocurrent gain and photoresponsivity that are hundreds to thousands of times higher than OPD, so it has more advantages in detecting weak light sources.

[0003] Generally speaking, in PhOFET, carrier transport only occurs in the organic photodetection layer, which is a two-dimensional transmission process, and the crystal state of the organic photodetection layer directly determines the performance of the prepared device. The organic photodetection layer is usually amorphous or polycrystalline, which is bound to bring various traps and scattering, and the carrier mobility will be greatly reduced, resulting in a decrease in the transmission and collection efficiency of the photogenerated carriers of PhOFET, thereby reducing the local light response. In addition, for the organic photodetection layer, there are very few materials that absorb light in the near-infrared and infrared bands, which also seriously limits the application of PhOFET in military radar and medical fields. At the same time, the source and drain of PhOFET are symmetrically arranged, the energy levels between the first electrode and the second electrode are the same, and electrons are not easy to flow between the two. The turn-on voltage and current switch of the device are relatively high, and the dark current is large. Summary of the invention

[0004] The purpose of the present application is to provide a photodetector and a method for preparing the same, so as to improve the spectral response range and local light response of the existing photodetector and reduce the turn-on voltage and current switching ratio of the device.

[0005] In order to achieve the above object, the present application provides a photoelectric detector, comprising:

[0006] Semiconductor substrate;

[0007] A photoelectric detection layer, located on the semiconductor substrate, comprising a stacked two-dimensional semiconductor photoelectric detection layer and an organic photoelectric detection layer; and

[0008] The first electrode and the second electrode are arranged in the photoelectric detection layer or on the photoelectric detection layer at intervals, and the first electrode and the second electrode are made of different materials.

[0009] Optionally, the material of the first electrode and the second electrode includes at least one of gold, silver, aluminum, copper, platinum and chromium.

[0010] Optionally, the two-dimensional semiconductor photodetection layer is located on the semiconductor substrate, and the organic photodetection layer is located on the two-dimensional semiconductor photodetection layer; or, the organic photodetection layer is located on the semiconductor substrate, and the two-dimensional semiconductor photodetection layer is located on the organic photodetection layer.

[0011] Optionally, the first electrode and the second electrode are located between the two-dimensional semiconductor photodetection layer and the organic photodetection layer.

[0012] Optionally, there is a bottom gate electrode layer and a bottom gate dielectric layer arranged in sequence from bottom to top between the semiconductor substrate and the photodetection layer; and / or, there is a top gate dielectric layer and a top gate electrode layer arranged in sequence from bottom to top on the photodetection layer.

[0013] Optionally, the semiconductor substrate is a bottom semiconductor layer and a buried oxide layer in a semiconductor-on-insulator substrate, and the bottom gate electrode layer is a top semiconductor layer in the semiconductor-on-insulator substrate.

[0014] Optionally, the bottom gate dielectric layer is an oxide layer naturally generated on the top semiconductor layer.

[0015] Optionally, the material of the two-dimensional semiconductor photodetection layer includes transition metal chalcogenides, black phosphorus, silicene, germanene or graphene; and / or, the material of the organic photodetection layer includes phthalocyanine metal compounds, naphthalocyanine metal compounds or pentacene.

[0016] The present invention also provides a method for preparing a photoelectric detector, comprising:

[0017] providing a semiconductor substrate;

[0018] forming a photodetection layer on the semiconductor substrate, wherein the photodetection layer comprises a stacked two-dimensional semiconductor photodetection layer and an organic photodetection layer; and,

[0019] A first electrode and a second electrode are formed in or on the photodetection layer and are spaced apart from each other. The first electrode and the second electrode are made of different materials.

[0020] Optionally, before forming the photodetection layer, a bottom gate electrode layer and a bottom gate dielectric layer are formed on the semiconductor substrate in sequence from bottom to top; and / or, after forming the photodetection layer, the first electrode and the second electrode, a top gate dielectric layer and a top gate electrode layer are formed on the photodetection layer in sequence from bottom to top.

[0021] Optionally, the semiconductor substrate is a bottom semiconductor layer and a buried oxide layer in a semiconductor-on-insulator substrate, the top semiconductor layer in the semiconductor-on-insulator substrate serves as the bottom gate electrode layer, and the naturally generated oxide layer on the top semiconductor layer serves as the bottom gate dielectric layer.

[0022] Optionally, the step of forming the photodetection layer, the first electrode and the second electrode comprises:

[0023] Forming the two-dimensional semiconductor photodetection layer and the support layer stacked in sequence on a mica substrate;

[0024] removing the mica substrate, transferring the two-dimensional semiconductor photodetection layer to the semiconductor base using the support layer, and removing the support layer;

[0025] forming the first electrode and the second electrode in steps on the two-dimensional semiconductor photodetection layer; and,

[0026] The organic photodetection layer is formed on the first electrode, the second electrode and the exposed two-dimensional semiconductor photodetection layer.

[0027] Optionally, the step of forming the photodetection layer, the first electrode and the second electrode comprises:

[0028] forming the organic photodetection layer on the semiconductor substrate;

[0029] forming the first electrode and the second electrode on the organic photodetection layer in steps;

[0030] forming the two-dimensional semiconductor photodetection layer and the support layer stacked in sequence on a mica substrate; and,

[0031] The mica substrate is removed, the two-dimensional semiconductor photodetection layer is transferred to the first electrode, the second electrode and the exposed organic photodetection layer using the support layer, and the support layer is removed.

[0032] The present application provides a photodetector and a method for preparing the same, wherein the photodetector comprises a semiconductor substrate, a photodetection layer, a first electrode and a second electrode, wherein the photodetection layer is located on the semiconductor substrate, and comprises a stacked two-dimensional semiconductor photodetection layer and an organic photodetection layer, wherein the first electrode and the second electrode are arranged at intervals in the photodetection layer or on the photodetection layer. In the present application, the spectral response range of the photodetection layer is the superposition of the spectral response ranges of the two-dimensional semiconductor photodetection layer and the organic photodetection layer. Since the spectral response ranges of the two are usually not completely overlapped, the photodetection layer can have a wider spectral response range and better local light responsivity; and the spectral response range of the two-dimensional semiconductor photodetection layer can usually cover the near-infrared and infrared bands, and the photodetector can be used in military radar and medical applications. In addition, the materials of the first electrode and the second electrode are different, forming an asymmetric source-drain electrode, reducing the barrier height, thereby reducing the dark current and increasing the photocurrent, thereby improving the device current switching ratio, responsivity and field effect mobility, and reducing the device turn-on voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A flow chart of a method for preparing a photodetector provided in an embodiment of the present application;

[0034] Figure 2 to Figure 10 The schematic diagram of the structure corresponding to the corresponding steps of the method for preparing the photoelectric detector provided in the embodiment of the present application, wherein: Fig.10 A schematic diagram of the structure of a photoelectric detector provided in an embodiment of the present application;

[0035] Wherein, the accompanying drawings are marked as follows:

[0036] 100-semiconductor substrate on insulator; 101-bottom semiconductor layer; 102-buried oxide layer; 103-top semiconductor layer; 201-bottom gate electrode layer; 202-top gate electrode layer; 301-bottom gate dielectric layer; 302-top gate dielectric layer; 401-two-dimensional semiconductor photodetection layer; 402-organic photodetection layer; 501-first electrode; 502-second electrode; 600-mica substrate; 700-support layer. DETAILED DESCRIPTION

[0037] The specific implementation of the present application will be described in more detail below in conjunction with the schematic diagram. Based on the following description, the advantages and features of the present application will become clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present application.

[0038] Fig.10 This is a schematic diagram of the structure of the photoelectric detector provided in this embodiment. Fig.10 As shown, in this embodiment, the photodetector is an organic photosensitive field effect transistor (PhOFET) for photoelectric detection. The photodetector includes a semiconductor substrate. The material of the semiconductor substrate can be, for example, at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, and also includes a multilayer structure composed of these semiconductors, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), etc. The material of the semiconductor substrate can also be a flexible material (such as polyimide, epoxy resin or silicone resin), etc.

[0039] A bottom gate electrode layer 201, a bottom gate dielectric layer 301, a photodetection layer, a first electrode 501, a second electrode 502, a top gate dielectric layer 302 and a top gate electrode layer 202 are formed on the semiconductor substrate, wherein the bottom gate electrode layer 201 is located on the semiconductor substrate, the bottom gate dielectric layer 301 is located on the bottom gate electrode layer 201, the photodetection layer is located on the bottom gate dielectric layer 301, the first electrode 501 and the second electrode 502 are located on the photodetection layer or in the photodetection layer, the top gate dielectric layer 302 is located on the photodetection layer, and the top gate electrode layer 202 is located on the top gate dielectric layer 302. Alternatively, it can also be considered that the semiconductor substrate, the bottom gate electrode layer 201, the bottom gate dielectric layer 301, the photodetection layer, the top gate dielectric layer 302 and the top gate electrode layer 202 are arranged in sequence from bottom to top, and the first electrode 501 and the second electrode 502 are arranged in the photodetection layer or on the photodetection layer at intervals.

[0040] In this embodiment, the semiconductor substrate is specifically a bottom semiconductor layer 101 and a buried oxide layer 102 in a semiconductor substrate on an insulator 100, that is, the semiconductor substrate includes a bottom semiconductor layer 101 and a buried oxide layer 102, and the bottom semiconductor layer 101 and the buried oxide layer 102 are arranged in sequence from bottom to top; the semiconductor substrate on an insulator 100 also includes a top semiconductor layer 103, and the top semiconductor layer 103 is located on the buried oxide layer 102. At this time, the top semiconductor layer 103 serves as the bottom gate electrode layer 201.

[0041] Optionally, the material of the bottom gate dielectric layer 301 can be an insulating oxide such as silicon oxide, silicon oxynitride, etc., and the material of the bottom gate electrode layer 201 can be a semiconductor material or a metal material, such as silicon, polysilicon, gold, silver, aluminum, copper, platinum, chromium and metal alloys thereof.

[0042] In some embodiments, the semiconductor substrate and the bottom gate electrode layer 201 may not be formed using the semiconductor-on-insulator substrate 100. For example, the semiconductor substrate may also be a conventional silicon semiconductor substrate, and then the bottom gate electrode layer 201 is formed on the semiconductor substrate. In this case, the bottom gate electrode layer 201 may be made of a semiconductor material or a metal material.

[0043] Further, the bottom gate dielectric layer 301 may be an oxide layer naturally generated on the top semiconductor layer 103. In this case, the material of the top semiconductor layer 103 may be silicon, and the material of the bottom gate dielectric layer 301 may be silicon oxide, but this should not be limiting. In some embodiments, the oxide layer naturally grown on the top semiconductor layer 103 may be removed first, and then a new oxide layer may be formed by a furnace oxidation process or a deposition process as the bottom gate dielectric layer 301. In this case, the film quality of the bottom gate dielectric layer 301 is higher. Alternatively, when the bottom gate electrode layer 201 is a metal material, a deposition process may be used to form the bottom gate dielectric layer 301 on the bottom gate dielectric layer 301.

[0044] Please continue reading Fig.10 The photodetection layer is located on the bottom gate dielectric layer 301, and includes a stacked two-dimensional semiconductor photodetection layer 401 and an organic photodetection layer 402. The organic photodetection layer 402 is located on the two-dimensional semiconductor photodetection layer 401. The first electrode 501 and the second electrode 502 are spaced apart on the two-dimensional semiconductor photodetection layer 401. The first electrode 501 and the second electrode 502 are sandwiched between the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402. In this way, the spectral response range of the photoelectric detection layer can superimpose the spectral response ranges of the two-dimensional semiconductor photoelectric detection layer 401 and the organic photoelectric detection layer 402. The spectral response range of the two-dimensional semiconductor photoelectric detection layer 401 is usually 400nm~1500nm, and the spectral response range of the organic photoelectric detection layer 402 is usually 200nm~980nm. The spectral response ranges of the two do not completely overlap. After the spectral response ranges of the two are superimposed, the photoelectric detection layer can achieve a wide spectral response range of 200nm~1500nm, and has better local light responsiveness in the band of 400nm~980nm. At this time, the spectral response range of the photoelectric detection layer also covers the near-infrared and infrared bands, so the photoelectric detector can be used in military radar and medical fields.

[0045] In this embodiment, the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 are arranged in sequence from bottom to top. Specifically, the two-dimensional semiconductor photodetection layer 401 is located on the bottom gate dielectric layer 301, and the organic photodetection layer 402 is located on the two-dimensional semiconductor photodetection layer 401, which is simpler to prepare. The first electrode 501 and the second electrode 502 are arranged on the two-dimensional semiconductor photodetection layer 401 at intervals, and the organic photodetection layer 402 is located on the first electrode 501, the second electrode 502 and the exposed two-dimensional semiconductor photodetection layer 401 to cover the first electrode 501 and the second electrode 502, and fill the gap between the first electrode 501 and the second electrode 502, that is, the first electrode 501 and the second electrode 502 are arranged in the photodetection layer at intervals, specifically, they are arranged between the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402. At this time, the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 are distributed on the upper and lower sides of the first electrode 501 and the second electrode 502, and the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 are very close to the conductive channel between the first electrode 501 and the second electrode 502. The two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 can play a roughly equivalent role in light absorption, and the photodetector can make use of the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 as much as possible.

[0046] In some embodiments, the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 are not limited to being stacked sequentially from bottom to top, and can also be swapped, that is, the two-dimensional semiconductor photodetection layer 401 can be located on the organic photodetection layer 402, specifically, the organic photodetection layer 402 can be located on the bottom gate dielectric layer 301, the first electrode 501 and the second electrode 502 are spaced apart on the organic photodetection layer 402, and the two-dimensional semiconductor photodetection layer 401 is located on the first electrode 501, the second electrode 502 and the exposed organic photodetection layer 402, thereby covering the first electrode 501 and the second electrode 502, and filling the gap between the first electrode 501 and the second electrode 502. At this time, the first electrode 501 and the second electrode 502 are also spaced apart in the photodetection layer, and specifically are also spaced apart between the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402.

[0047] In some embodiments, the positions of the first electrode 501 and the second electrode 502 may be changed, and the first electrode 501 and the second electrode 502 may be arranged on the photodetection layer or arranged in the two-dimensional semiconductor photodetection layer 401 or the organic photodetection layer 402 at intervals. For example, Fig.10 In the embodiment, the first electrode 501 and the second electrode 502 may also be arranged at intervals on the organic photodetection layer 402, or at intervals in the two-dimensional semiconductor photodetection layer 401 or the organic photodetection layer 402. In other words, the specific positions of the first electrode 501 and the second electrode 502 do not affect the implementation of the present application. When the preparation process allows, the first electrode 501 and the second electrode 502 may even be arranged in the two-dimensional semiconductor photodetection layer 401 or in the organic photodetection layer 402.

[0048] Optionally, the material of the two-dimensional semiconductor photodetection layer 401 may be at least one of transition metal chalcogenides, black phosphorus, silicene, germanene or graphene, and the material of the organic photodetection layer 402 may be at least one of phthalocyanine metal compounds (such as lead phthalocyanine, copper phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, cobalt phthalocyanine, iron phthalocyanine, etc.), naphthalocyanine metal compounds or pentacene.

[0049] Further, in this embodiment, the materials of the first electrode 501 and the second electrode 502 are different. For example, the material of the first electrode 501 may be gold, and the material of the second electrode 502 may be silver, but it should not be limited thereto. The materials of the first electrode 501 and the second electrode 502 may include at least one of gold, silver, aluminum, copper, platinum and chromium. Since the materials of the first electrode 501 and the second electrode 502 are different, an asymmetric source-drain electrode is formed. In particular, when two metal materials with a large work function difference are used, the energy level difference is large and usually different, which can greatly reduce the Schottky barrier between the first electrode 501 and the second electrode 502. Electrons are more likely to flow between the first electrode 501 and the second electrode 502, thereby reducing dark current and increasing photocurrent, thereby increasing the device current switching ratio and reducing the device turn-on voltage. Since the responsivity is related to the photocurrent and the incident light power, after the photocurrent is increased, the responsivity and field effect mobility are both increased.

[0050] Please continue reading Fig.10In this embodiment, the photodetector has two gates, namely the bottom gate electrode layer 201 and the top gate electrode layer 202. The bottom gate electrode layer 201 and the top gate electrode layer 202 are respectively located on the upper and lower sides of the photodetection layer, thereby forming an upper and lower double-gate structure. The double-gate structure can enhance the control performance of the conductive channel of the photodetector and obtain a larger output current at a lower operating voltage. Compared with the single-gate structure (only the bottom gate electrode layer 201 or only the top gate electrode layer 202), the field effect mobility and the current switching ratio are higher. In some embodiments, the photodetector can also be a single-gate structure. In this case, the bottom gate electrode layer 201 and the bottom gate dielectric layer 301 can be omitted, or the top gate electrode layer 202 can be omitted.

[0051] In this embodiment, the top surface of the top gate electrode layer 202 is the light incident surface. In order to avoid shading, the top gate dielectric layer 302 and the top gate electrode layer 202 are preferably transparent film layers, and the transmittance can be greater than 90%, thereby avoiding adverse effects on the light responsiveness of the photodetector.

[0052] Optionally, the material of the top gate dielectric layer 302 may be an organic polymer, such as Parylene C, Polymethyl Methacrylate (PMMA), polyimide, polyvinyl alcohol, etc., so as to simplify the preparation process of the top gate dielectric layer 302. Of course, the material of the top gate dielectric layer 302 may also be an insulating oxide, such as silicon oxide, silicon oxynitride, etc. The material of the top gate electrode layer 202 may be a material such as ITO.

[0053] Based on this, this embodiment also provides a method for preparing a photoelectric detector. Figure 1 The flowchart of the method for preparing the photoelectric detector provided in this embodiment is as follows: Figure 1 As shown, the preparation method of the photodetector includes:

[0054] Step S100: providing a semiconductor substrate;

[0055] Step S200: forming a photoelectric detection layer on the semiconductor substrate, wherein the photoelectric detection layer includes a stacked two-dimensional semiconductor photoelectric detection layer and an organic photoelectric detection layer; and,

[0056] Step S300: forming a first electrode and a second electrode spaced apart in or on the photodetection layer, wherein the first electrode and the second electrode are made of different materials.

[0057] Figure 2 to Figure 10 The following is a schematic diagram of the structure corresponding to the corresponding steps of the method for preparing the photoelectric detector provided in this embodiment. Figure 2 to Figure 10 The preparation method of the photoelectric detector provided in this embodiment is described in detail.

[0058] like Figure 2 As shown, step S100 is performed, first providing a semiconductor-on-insulator substrate 100, the semiconductor-on-insulator substrate 100 comprising a bottom semiconductor layer 101, a buried oxide layer 102 and a top semiconductor layer 103 arranged in sequence from bottom to top, and an oxide layer is naturally grown on the top semiconductor layer 103. The semiconductor-on-insulator substrate 100 is washed with acetone, ethanol and deionized water in sequence for about 10 minutes, and then the semiconductor-on-insulator substrate 100 is placed in a vacuum drying oven, and the semiconductor-on-insulator substrate 100 is dried in an environment of about 60° C. for about 30 minutes and then taken out.

[0059] Afterwards, the bottom semiconductor layer 101 and the buried oxide layer 102 can serve as the semiconductor substrate of the photodetector, the top semiconductor layer 103 can serve as the bottom gate electrode layer 201 of the photodetector, and the oxide layer naturally grown on the top semiconductor layer 103 can serve as the bottom gate dielectric layer 301 of the photodetector.

[0060] As an optional embodiment, a substrate such as a silicon semiconductor substrate can be directly used as the semiconductor substrate of the photodetector, and then the bottom gate electrode layer 201 and the bottom gate dielectric layer 301 are sequentially formed on the semiconductor substrate. In order to improve the quality of the bottom gate dielectric layer 301, the naturally grown oxide layer on the top semiconductor layer 103 can also be removed first, and then a good quality oxide layer can be re-formed on the top semiconductor layer 103 using a furnace tube oxidation process. Among them, the silicon semiconductor substrate can also be replaced by Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductor substrates, or multilayer structures composed of these semiconductors, or semiconductor substrates such as silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), and can also be replaced by a semiconductor substrate made of a flexible material (such as polyimide, epoxy resin or silicone resin).

[0061] Next, step S200 and step S300 are performed, as shown in FIG. Figure 3 As shown, the two-dimensional semiconductor photodetection layer 401 (which can be prepared by van der Waals epitaxy) is formed on the mica substrate 600, and the two-dimensional semiconductor photodetection layer 401 covers the mica substrate 600. Figure 4As shown, a support layer 700 is formed on the two-dimensional semiconductor photodetection layer 401, and the support layer 700 covers the two-dimensional semiconductor photodetection layer 401. The material of the support layer 700 can be a high molecular polymer material. Fig.10 As shown, the mica substrate 600 is soaked in isopropyl alcohol so that the mica substrate 600 falls off from the two-dimensional semiconductor photodetection layer 401, and then the two-dimensional semiconductor photodetection layer 401 is transferred to the bottom gate dielectric layer 301 by a wet transfer process. For example, the material of the two-dimensional semiconductor photodetection layer 401 can be black phosphorus, and the material of the support layer 700 can be PMMA. After the mica substrate 600 is detached, PMMA is used to support the black phosphorus film, and the black phosphorus film is transferred to the bottom gate dielectric layer 301 by a wet transfer process based on PMMA, that is, the two-dimensional semiconductor photodetection layer 401 is formed on the bottom gate dielectric layer 301. Figure 6 As shown, the support layer 700 is removed to expose the two-dimensional semiconductor photodetection layer 401.

[0062] Optionally, the material of the two-dimensional semiconductor photodetection layer 401 may be at least one of transition metal chalcogenides, black phosphorus, silicene, germanene or graphene.

[0063] like Figure 7 As shown, a metal material is vacuum evaporated on the two-dimensional semiconductor photodetection layer 401 to form the first electrode 501. Figure 8 As shown, another metal material is vacuum evaporated on the two-dimensional semiconductor photodetection layer 401 to form the second electrode 502. The shapes of the first electrode 501 and the second electrode 502 can be controlled by a mask, that is, when evaporating the metal material, the area on the two-dimensional semiconductor photodetection layer 401 that does not need to be covered with the metal material needs to be blocked with a mask, and the mask can limit the conductive channel length and the area of ​​the first electrode 501 and the second electrode 502. After the vacuum evaporation is completed, the mask is removed. In some embodiments, a magnetron sputtering process can also be used to sputter the metal material on the two-dimensional semiconductor photodetection layer 401.

[0064] The materials of the first electrode 501 and the second electrode 502 are different. For example, the material of the first electrode 501 can be gold, and the material of the second electrode 502 can be silver, but it should not be limited to this. The materials of the first electrode 501 and the second electrode 502 can include at least one of gold, silver, aluminum, copper, platinum and chromium. Since the materials of the first electrode 501 and the second electrode 502 are different, an asymmetric source-drain electrode is formed. In particular, when two metal materials with a large work function difference are used, the energy level difference is large and usually different, which can greatly reduce the Schottky barrier between the first electrode 501 and the second electrode 502. Electrons are more likely to flow between the first electrode 501 and the second electrode 502, thereby reducing dark current and increasing photocurrent, thereby increasing the device current switching ratio and reducing the device turn-on voltage. Since the responsivity is related to the photocurrent and the incident light power, after the photocurrent is increased, the responsivity and field effect mobility are both improved.

[0065] like Fig. 9 As shown, an organic semiconductor material is vacuum evaporated on the first electrode 501, the second electrode 502 and the exposed two-dimensional semiconductor photodetection layer 401 to form the organic photodetection layer 402. After the evaporation is completed, the organic photodetection layer 402 will cover the first electrode 501, the second electrode 502 and fill the gap between the first electrode 501 and the second electrode 502. The two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402 together constitute the photodetection layer of the photodetector.

[0066] Optionally, the material of the organic photodetection layer 402 may be at least one of a phthalocyanine metal compound (such as lead phthalocyanine, copper phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, cobalt phthalocyanine, iron phthalocyanine, etc.), a naphthalocyanine metal compound or pentacene.

[0067] In some embodiments, the organic semiconductor material may be vacuum evaporated on the bottom gate dielectric layer 301 to form the organic photodetection layer 402. After the evaporation is completed, the organic photodetection layer 402 will cover the bottom gate dielectric layer 301. Then the first electrode 501 and the second electrode 502 are formed step by step on the organic photodetection layer 402. After that, the two-dimensional semiconductor photodetection layer 401 and the support layer 700 stacked in sequence are formed on the mica substrate 600. After separating the mica substrate 600, the two-dimensional semiconductor photodetection layer 401 is transferred to the first electrode 501, the second electrode 502 and the exposed two-dimensional semiconductor photodetection layer 401 by a wet transfer process, and finally the support layer 700 is removed. In this way, the two-dimensional semiconductor photodetection layer 401 will be located on the organic photodetection layer 402, and the first electrode 501 and the second electrode 502 are still located between the two-dimensional semiconductor photodetection layer 401 and the organic photodetection layer 402.

[0068] It should be noted that the first electrode 501 and the second electrode 502 can also be formed in other steps. For example, the first electrode 501 and the second electrode 502 can be formed in steps after the photodetection layer is formed. At this time, the first electrode 501 and the second electrode 502 can be located on the photodetection layer.

[0069] like Fig.10 As shown, a top gate dielectric layer 302 is formed on the photodetection layer, and a top gate electrode layer 202 is formed on the top gate dielectric layer 302. In this embodiment, the material of the top gate dielectric layer 302 is polyparaxylene (ParyleneC), and the material of the top gate electrode layer 202 is ITO. Therefore, the top gate dielectric layer 302 and the top gate electrode layer 202 can be formed by a magnetron sputtering process, thereby eliminating the need to change the machine, simplifying the photodetector preparation process.

[0070] In this embodiment, the photodetector has two gates, namely the bottom gate electrode layer 201 and the top gate electrode layer 202, and the bottom gate electrode layer 201 and the top gate electrode layer 202 are respectively located on the upper and lower sides of the photodetection layer, thereby forming an upper and lower double-gate structure, and the double-gate structure can enhance the control performance of the conductive channel of the photodetector, and can obtain a larger output current at a lower operating voltage. Compared with the single-gate structure (only the bottom gate electrode layer 201 or only the top gate electrode layer 202), the field effect mobility and the current switching ratio are higher. It should be noted that when the photodetector is a single-gate structure, the step of preparing the top gate electrode layer 202 or the step of preparing the bottom gate electrode layer 201 and the bottom gate dielectric layer 301 can be omitted.

[0071] In summary, in the photodetector and its preparation method provided in the embodiment of the present application, the photodetector includes a semiconductor substrate, a photodetection layer, a first electrode and a second electrode, the photodetection layer is located on the semiconductor substrate, including a stacked two-dimensional semiconductor photodetection layer and an organic photodetection layer, and the first electrode and the second electrode are arranged in the photodetection layer or on the photodetection layer. In the present application, the spectral response range of the photodetection layer is the superposition of the spectral response ranges of the two-dimensional semiconductor photodetection layer and the organic photodetection layer. Since the spectral response ranges of the two are usually not completely overlapped, the photodetection layer can have a wider spectral response range and better local light responsivity; and the spectral response range of the two-dimensional semiconductor photodetection layer can usually cover the near-infrared and infrared bands, which can realize the application of the photodetector in military radar and medical fields. In addition, the materials of the first electrode and the second electrode are different, forming an asymmetric source-drain electrode, reducing the barrier height, thereby reducing the dark current and increasing the photocurrent, thereby improving the device current switching ratio, responsivity and field effect mobility, and reducing the device turn-on voltage.

[0072] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0073] It should also be noted that, although the present application has been disclosed as above with preferred embodiments, the above embodiments are not intended to limit the present application. For any technician familiar with the art, without departing from the scope of the technical solution of the present application, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present application, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

[0074] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are merely used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0075] It should also be recognized that the terms described herein are only used to describe specific embodiments and are not used to limit the scope of the present application. It should be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have a definition of logical "or", rather than a definition of logical "exclusive or", unless the context clearly indicates the opposite meaning. In addition, the implementation of the method and / or device in the embodiment of the present application may include performing the selected task manually, automatically, or in combination.

Claims

1. A photoelectric detector, characterized in that: include: Semiconductor substrate; A photoelectric detection layer, located on the semiconductor substrate, includes a stacked two-dimensional semiconductor photoelectric detection layer and an organic photoelectric detection layer; as well as, The first electrode and the second electrode are arranged in the photoelectric detection layer or on the photoelectric detection layer at intervals, and the first electrode and the second electrode are made of different materials.

2. The photodetector according to claim 1, wherein: The material of the first electrode and the second electrode includes at least one of gold, silver, aluminum, copper, platinum and chromium.

3. The photodetector according to claim 1, wherein: The two-dimensional semiconductor photodetection layer is located on the semiconductor substrate, and the organic photodetection layer is located on the two-dimensional semiconductor photodetection layer; or, the organic photodetection layer is located on the semiconductor substrate, and the two-dimensional semiconductor photodetection layer is located on the organic photodetection layer.

4. The photodetector according to claim 3, characterized in that The first electrode and the second electrode are located between the two-dimensional semiconductor photodetection layer and the organic photodetection layer.

5. The photodetector according to claim 1, wherein: A bottom gate electrode layer and a bottom gate dielectric layer are arranged in sequence from bottom to top between the semiconductor substrate and the photodetection layer; and / or a top gate dielectric layer and a top gate electrode layer are arranged in sequence from bottom to top on the photodetection layer.

6. The photodetector according to claim 5, characterized in that The semiconductor substrate is a bottom semiconductor layer and a buried oxide layer in a semiconductor-on-insulator substrate, and the bottom gate electrode layer is a top semiconductor layer in the semiconductor-on-insulator substrate.

7. The photodetector according to claim 6, wherein: The bottom gate dielectric layer is an oxide layer naturally generated on the top semiconductor layer.

8. The photodetector according to claim 1, wherein: The material of the two-dimensional semiconductor photodetection layer includes transition metal chalcogenides, black phosphorus, silicene, germanene or graphene; and / or the material of the organic photodetection layer includes phthalocyanine metal compounds, naphthalocyanine metal compounds or pentacene.

9. A method for preparing a photoelectric detector, characterized in that: include: providing a semiconductor substrate; forming a photoelectric detection layer on the semiconductor substrate, wherein the photoelectric detection layer comprises a stacked two-dimensional semiconductor photoelectric detection layer and an organic photoelectric detection layer; as well as, A first electrode and a second electrode are formed in or on the photodetection layer and are spaced apart from each other. The first electrode and the second electrode are made of different materials.

10. The method for preparing a photodetector according to claim 9, characterized in that: Before forming the photodetection layer, a bottom gate electrode layer and a bottom gate dielectric layer are formed on the semiconductor substrate in sequence from bottom to top; and / or, after forming the photodetection layer, the first electrode and the second electrode, a top gate dielectric layer and a top gate electrode layer are formed on the photodetection layer in sequence from bottom to top.

11. The method for preparing a photodetector according to claim 10, characterized in that: The semiconductor substrate is a bottom semiconductor layer and a buried oxide layer in a semiconductor-on-insulator substrate, the top semiconductor layer in the semiconductor-on-insulator substrate serves as the bottom gate electrode layer, and the naturally generated oxide layer on the top semiconductor layer serves as the bottom gate dielectric layer.

12. The method for preparing a photodetector according to any one of claims 9 to 11, characterized in that: The steps of forming the photodetection layer, the first electrode and the second electrode include: Forming the two-dimensional semiconductor photodetection layer and the support layer stacked in sequence on a mica substrate; removing the mica substrate, transferring the two-dimensional semiconductor photodetection layer to the semiconductor base using the support layer, and removing the support layer; forming the first electrode and the second electrode in steps on the two-dimensional semiconductor photodetection layer; and, The organic photodetection layer is formed on the first electrode, the second electrode and the exposed two-dimensional semiconductor photodetection layer.

13. The method for preparing a photodetector according to any one of claims 9 to 11, characterized in that: The steps of forming the photodetection layer, the first electrode and the second electrode include: forming the organic photodetection layer on the semiconductor substrate; forming the first electrode and the second electrode on the organic photodetection layer in steps; forming the two-dimensional semiconductor photodetection layer and the support layer stacked in sequence on a mica substrate; and, The mica substrate is removed, the two-dimensional semiconductor photodetection layer is transferred to the first electrode, the second electrode and the exposed organic photodetection layer using the support layer, and the support layer is removed.

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