Sandwich silicon-based heterojunction self-energized broadband photoelectric detector based on Sb2O3 carrier barrier layer and preparation method of sandwich silicon-based heterojunction self-energized broadband photoelectric detector

Abstract

The invention discloses a sandwich silicon-based heterojunction self-energized broadband photoelectric detector based on a Sb2O3 carrier barrier layer and a preparation method thereof, a Sb2O3 intermediate layer is prepared on a cleaned and pre-masked silicon substrate through an electron beam evaporation method to play a carrier blocking role, then a bismuth compound film is prepared on the Sb2O3 layer, and the Sb2O3 intermediate layer and the bismuth compound film are combined to form the Sb2O3 heterojunction self-energized broadband photoelectric detector based on the Sb2O3 carrier barrier layer. And finally, preparing a pair of electrodes on the surfaces of the silicon substrate and the bismuthide film to obtain the bismuthide / Sb2O3 / silicon sandwich heterojunction photoelectric detector. Compared with a bismuth compound / silicon heterojunction detector, the existence of the Sb2O3 carrier barrier layer can effectively reduce dark current and improve light current, excellent detection performance on ultraviolet-visible-infrared bands under the condition of room temperature and without external bias voltage is achieved, the detection rate and responsivity are improved by 2-4 orders of magnitude, the maximum is 1012 Jones and 10 <-1 > A / W, and the detection efficiency and responsivity are improved by 2-4 orders of magnitudes, the maximum is 10 <-1 > Jones and 10 <-1 > A / W. And meanwhile, excellent stability and a unit device imaging function are realized.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor devices, and relates to a self-powered broadband photodetector, specifically to a sandwich silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer and a preparation method thereof. Background Art

[0002] The self-powered broadband photodetector has the function of detecting optical signals in the ultraviolet-visible-infrared light range under zero bias voltage, and has wide applications in the fields of imaging, optical communication, remote sensing technology, environmental detection, biosensing, optical switches, etc. However, most of the current photodetectors are only for specific bands. In the face of the demand for broadband detection, the method of integrating multiple detectors is generally adopted, which increases the complexity of the system and energy consumption, and it is difficult to meet the future requirements for low-power and high-performance devices. The vertical heterojunction is a structure that can effectively achieve broadband self-powered detection, and it has the following advantages: (1) The built-in electric field can be generated in the junction region formed at the interface, effectively separating photo-generated electrons and holes to achieve the self-powered characteristic; (2) It has the light response performance of multiple material components in different bands at the same time, and can effectively expand the response band; (3) High-density device integration can be achieved, which is an important development direction of optoelectronic integrated chips.

[0003] Introducing a carrier blocking layer into the vertical heterojunction to construct a sandwich structure for energy band design can effectively reduce the dark current, inhibit carrier recombination, and effectively improve the performance of the detector. Metal oxides with relatively wide band gaps are typical materials for the carrier blocking layer of heterojunctions. For example, In2O3 and TiO2 are used as the intermediate layers of sandwich heterojunction photodetectors, achieving a reduction in dark current and an increase in photocurrent, and obtaining high-detection-rate SnO2 / In2O3 / SnS2 and perovskite / TiO2 / Si heterojunction photodetectors. In view of the rapid development of silicon-based optoelectronic integrated chips, there is an urgent need to develop a silicon-based sandwich heterojunction photodetector containing a carrier blocking layer to achieve high-performance broadband detection under zero bias voltage. Summary of the Invention

[0004] The present invention provides a sandwich silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer and a preparation method thereof. An Sb2O3 intermediate layer is prepared on a cleaned and pre-masked silicon substrate by electron beam evaporation, which plays a role in carrier blocking. Subsequently, a bismuth compound film is prepared on the Sb2O3 layer, and finally, a pair of electrodes are prepared on the surfaces of the silicon substrate and the bismuth compound film to obtain a bismuth compound / Sb2O3 / silicon sandwich heterojunction photodetector. Compared with a bismuth compound / silicon heterojunction detector, the presence of the Sb2O3 carrier blocking layer can effectively reduce the dark current and increase the photocurrent, achieving excellent detection performance in the ultraviolet-visible-infrared band (254 - 1050 nm) at room temperature without an external bias voltage. Its detectivity and responsivity are increased by 2 - 4 orders of magnitude, up to 10 12 Jones and 10 -1 A / W, and it also has excellent stability and the imaging function of a single device.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A sandwich silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer includes a silicon substrate, an Sb2O3 intermediate layer, a bismuth compound layer, and a pair of electrodes, wherein:

[0007] The silicon substrate is used for light response and can be one of an n-type silicon substrate or a p-type silicon substrate;

[0008] The Sb2O3 intermediate layer plays a role in carrier blocking, and its thickness is 5 nanometers to 1 micrometer;

[0009] The bismuth compound layer is used for light response and is one of bismuth selenide or bismuth telluride thin films, and its thickness is less than 1 micrometer;

[0010] The pair of electrodes are respectively located on the surfaces of the silicon substrate and the bismuth compound layer and are used for current collection. Among them, the electrode material located on the surface of the silicon substrate can be one or any combination of several materials such as Ti, Au, Ag, Cu, Pt, Al, Cr, In, graphene (such as Ti / Au, Cr / Au, etc.), and its thickness is less than 1 micrometer, and its shape and size are not limited; the electrode material located on the surface of the bismuth compound layer can be one or any combination of several materials such as Ti, Au, Ag, Cu, Pt, Al, Cr, In, graphene (such as Ti / Au, Cr / Au, etc.), and its thickness is less than 1 micrometer, and its shape and size are not limited; the compositions of the electrode material located on the surface of the silicon substrate and the electrode material located on the surface of the bismuth compound layer can be the same or different.

[0011] A preparation method of the above-mentioned sandwich silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer includes the following steps:

[0012] Step 1: Clean the silicon substrate;

[0013] Step 2: Fix a mask on the silicon substrate to expose part of the silicon surface, and deposit an Sb2O3 layer on the exposed area of the silicon substrate by using an electron beam evaporation device. Among them, when preparing the Sb2O3 layer by using the electron beam evaporation device, the vacuum degree is not higher than 10 -4 Pa, and the deposition rate is

[0014] Step 3: Prepare a bismuth compound layer on the surface of the Sb2O3 layer. Among them, the bismuth compound layer can be directly prepared on the surface of the Sb2O3 layer by electron beam evaporation, magnetron sputtering or chemical / physical vapor deposition method, or a bismuth compound thin film can be transferred to the surface of the Sb2O3 layer;

[0015] Step 4: Anneal the bismuth compound / Sb2O3 / silicon sandwich heterojunction to optimize the crystallization quality of the material. Among them, the annealing temperature is 150 - 300 °C, the annealing time is 10 - 360 minutes, and the annealing atmosphere is argon;

[0016] Step 5: Prepare an electrode on the surface of the silicon substrate. Among them, the electrode preparation method can be electron beam evaporation, thermal evaporation, wet transfer or dry transfer;

[0017] Step 6: Prepare an electrode on the surface of the bismuth compound. Among them, the electrode preparation method can be electron beam evaporation, thermal evaporation, wet transfer or dry transfer.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The sandwich silicon-based heterojunction self-powered broadband photodetector of the present invention has the self-powered characteristic, can realize the detection of optical signals in the ultraviolet-visible-infrared light band under room temperature conditions and without an external bias voltage, has low power consumption, has the broadband photodetection function, has a high detection rate, and is sensitive in response.

[0020] 2. The present invention prepares a high-quality Sb2O3 intermediate layer by electron beam evaporation technology supplemented by low-temperature annealing, realizes the function of a carrier blocking layer, can effectively reduce the dark current, and shows excellent photodetection ability and stability. Compared with the bismuth compound / silicon heterojunction without the Sb2O3 intermediate layer, the detection rate and responsivity are greatly improved.

[0021] 3. The detector of the present invention also has the imaging function of multi-band unit devices. Description of the Drawings

[0022] Figure 1 Atomic force microscope image of the Sb2O3 / Si heterojunction prepared for Example 1;

[0023] Figure 2 Atomic force microscopy image of the Bi2Te3 / Sb2O3 / Si heterojunction prepared in Example 1;

[0024] Figure 3 Schematic diagram of the structure of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in Example 1;

[0025] Figure 4 Optical photograph of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in Example 1;

[0026] Figure 5 Raman spectrum and X-ray diffraction spectrum of the Sb2O3 carrier blocking layer prepared in Example 1;

[0027] Figure 6 On / off photocurrent-time curves of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in Example 1 under illumination at 254 nm, 365 nm, 470 nm, 530 nm, 625 nm, 850 nm, 970 nm and 1050 nm without an external bias voltage;

[0028] Figure 7 On / off photocurrent-time 100-cycle curves of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in Example 1 under 850 nm light illumination without an external bias voltage in the fresh state and after 6 months;

[0029] Figure 8 Imaging diagrams of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in Example 1 as a single-pixel sensing unit under ultraviolet (365 nm), visible (530 nm) and infrared light (850 nm) illumination;

[0030] Figure 9 Atomic force microscopy image of the Bi2Te3 / Si heterojunction prepared in Comparative Example 1;

[0031] Figure 10 Photocurrent and dark current of the photodetectors described in Comparative Example 1 and Example 1 under light illumination of different wavelengths;

[0032] Figure 11 Detectivity and responsivity of the photodetectors described in Comparative Example 1 and Example 1 under light illumination of different wavelengths;

[0033] Figure 12 Schematic diagram of the structure of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector described in Example 2. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0035] Example 1:

[0036] A preparation method of a Bi2Te3 / Sb2O3 / Si heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer is as follows: Clean the p-type silicon substrate, fix the mask on the silicon substrate, fix its surface downward in the sample area of the electron beam evaporation equipment, and turn on the electron beam evaporation equipment to prepare the Sb2O3 layer on the silicon surface. During the preparation process, the chamber vacuum degree is 10 -4 Pa, the evaporation rate is about / s, the time is 15 min, and the Sb2O3 / Si heterojunction is obtained. The thickness of the Sb2O3 layer is about 50 nm (as Figure 1 shown). Subsequently, using Bi2Te3 powder as the source, a Bi2Te3 thin film is prepared on the surface of the Sb2O3 layer through the electron beam evaporation equipment. During the preparation process, the chamber vacuum degree is 10 -4 Pa, the evaporation rate is / s, the time is 30 min, and the Bi2Te3 / Sb2O3 / Si heterojunction is obtained. The thickness of the Bi2Te3 / Sb2O3 layer is 126 nm (as Figure 2 shown). Place the sample in a tube furnace for annealing treatment to improve the crystallization quality of the material. The annealing temperature is 250 °C, the annealing time is 60 min, and the annealing atmosphere is argon. Fix the electrode mask on the surface of the obtained Bi2Te3 / Sb2O3 / Si heterojunction, and use the electron beam evaporation equipment to prepare a pair of rectangular silver electrodes on the surface of the silicon substrate and the Bi2Te3 thin film. The evaporation rate is / s, the time is 40 min, the thickness is about 40 nm, and the electrode spacing is 0.25 mm. The Bi2Te3 / Sb2O3 / Si heterojunction photodetector is obtained, and its structural schematic diagram is as Figure 3 shown, and the top-view optical microscope photo is as Figure 4 shown.

[0037] Figure 5 Shown are the Raman spectrum and X-ray diffraction (XRD) spectrum of the Sb2O3 carrier blocking layer. The Raman spectrum shows the Raman characteristic peaks of the cubic phase of Sb2O3, located at 122.9 cm -1 (E g ), 193.8 cm -1 (F 2g ), 257.9 cm -1 (A 1g ), 378.8 cm-1 (F 2g ) and 454.5 cm -1 (A g ), and the Raman characteristic peaks of the Sb2O3 orthorhombic phase are located at 303.6 cm -1 (E g ). Similarly, by comparing the X-ray diffraction spectrum of the Sb2O3 layer with the standard card, it is found that both the cubic phase and the orthorhombic phase coexist in the Sb2O3 layer, but the proportion of the orthorhombic phase is relatively low, indicating that the Sb2O3 layer synthesized in this example is mainly the cubic phase of Sb2O3. In addition, the Raman and XRD characteristic peaks are sharp, indicating that the crystallization quality of the Sb2O3 layer is relatively high.

[0038] The two electrodes of the Bi2Te3 / Sb2O3 / Si heterojunction photodetector are connected to a semiconductor analyzer through a probe station for photoelectric performance testing. At room temperature and without an external bias voltage, the light source is irradiated on the photosensitive area (between the two electrodes) of the detector, and the light source is periodically turned on / off to test the photocurrent-time curve between the two electrodes, as Figure 6 shown. The incident light sources include ultraviolet (254 nm, 365 nm), visible (470 nm, 530 nm, 625 nm) and infrared light (850 nm, 970 nm, 1050 nm), and the optical power density is marked in Figure 6 . As can be seen from Figure 6 , the Bi2Te3 / Sb2O3 / Si heterojunction photodetector prepared in this example exhibits the detection ability for ultraviolet-visible-infrared broadband optical signals. The photocurrent remains stable and the response is rapid within multiple cycles, indicating that the detector prepared in this example has excellent self-powered broadband detection performance. Further, the stability test of the 850 nm optical signal Figure 7 shows the current-time curves of the detector prepared in this example in the fresh state and after being stored in a vacuum drying tower for 6 months within 100 cycles, both of which exhibit stable light responses. After 6 months, the photocurrent only decays by 0.05 μA (~3%), proving that the photodetector prepared in this example has good cycle stability and long-term storage stability.

[0039] Further illustrate the imaging function of the unit device of the photodetector prepared in this embodiment. Fix the imaging target template engraved with the letter "HIT" on the scanning bracket in the imaging system, and place it between the light source and the detector. Use a computer program to move the imaging target template in the plane to achieve the scanning of the target image. During the scanning process, record the position of the target image, and at the same time measure the current of the detector without an external bias voltage to establish the relationship between the position and the current. The wavelengths of the incident light source are selected as 365 nm, 530 nm, and 850 nm. When the light source is blocked by the target image template, the measured current level is low, which is the dark current; when the light source is incident on the detector through the "HIT" etching area, the current level is high, which is the bright current. Through further processing by the computer program, the current signal related to the position can be converted into the target image "HIT", as Figure 8 shown, the target image is clear, proving that the heterojunction photodetector prepared in this embodiment has the self-powered broadband imaging function.

[0040] Comparative Example 1:

[0041] This comparative example demonstrates the optoelectronic performance of the Bi2Te3 / Si heterojunction photodetector, aiming to illustrate the improvement effect of the Sb2O3 carrier blocking layer on the performance of the silicon-based heterojunction photodetector. Compared with the preparation process of Example 1, the preparation process of the Bi2Te3 / Si heterojunction photodetector only cancels the electron beam evaporation preparation process of the Sb2O3 layer, and other steps are exactly the same, including silicon wafer cleaning, preparation of the Bi2Te3 thin film on the silicon substrate surface, annealing, and Ag electrode preparation. The thickness of the Bi2Te3 thin film in the Bi2Te3 / Si heterojunction described in Comparative Example 1 is about 79 nm, and its atomic force microscope photograph is as Figure 9 shown.

[0042] Same as Example 1, under room temperature and without an external bias voltage, measure the current-time curve of the Bi2Te3 / Si heterojunction photodetector, and use the same ultraviolet (365 nm), visible (470 nm, 530 nm, 625 nm), and infrared light (850 nm, 970 nm, 1050 nm) light sources. The optical power density is marked in Figure 10 in. Figure 10 Shows the photocurrent and dark current of the Bi2Te3 / Sb2O3 / Si and Bi2Te3 / Si heterojunction photodetectors described in Example 1 under different illuminations. It can be found that after introducing the Sb2O3 carrier blocking layer, the dark current decreases, and the photocurrent increases by about 2 to 4 orders of magnitude. Figure 11 To calculate the detectivity and responsivity of the two photodetectors at different wavelengths, compared with Bi2Te3 / Si, the responsivity and detectivity of the Bi2Te3 / Sb2O3 / Si photodetector are increased by 3 to 4 orders of magnitude, and the detectivity is about 10 11 ~10 12Jones, the responsivity is about 10 -2 ~10 - 1 A / W. By comparison, it can be seen that the detection performance of the sandwich silicon-based heterojunction photodetector based on the Sb2O3 carrier blocking layer has been significantly improved, and the device structure is advanced.

[0043] Example 2:

[0044] A preparation method of a Bi2Te3 / Sb2O3 / Si heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer is as follows: Clean the p-type silicon substrate, fix the mask on the silicon substrate, fix its surface downward in the sample area of the electron beam evaporation equipment, and turn on the electron beam evaporation equipment to prepare the Sb2O3 layer on the silicon surface. During the preparation process, the chamber vacuum is 10 -4 Pa, and the evaporation rate is about / s, and the time is 20 min to obtain the Sb2O3 / Si heterojunction. Subsequently, using Bi2Te3 powder as the source, a Bi2Te3 thin film is prepared on the surface of the Sb2O3 layer through an electron beam evaporation equipment. During the preparation process, the chamber vacuum is 10 -4 Pa, and the evaporation rate is / s, and the time is 20 min to obtain the Bi2Te3 / Sb2O3 / Si heterojunction. Place the sample in a tube furnace for annealing treatment to improve the material crystallization quality. The annealing temperature is 250 °C, the annealing time is 60 min, and the annealing atmosphere is argon. The graphene / Ag electrode is prepared by dry transfer, and the process is as follows: First, graphene nanosheets are prepared by mechanical exfoliation and transferred to the Si / SiO2 substrate; Second, on the two-dimensional material transfer platform, pick up the graphene nanosheets with PDMS and transfer one graphene nanosheet electrode on the surface of the bismuth compound and the silicon wafer respectively; Finally, fix the electrode mask and evaporate Ag to connect with the graphene electrode. The schematic diagram of the device structure is shown in Figure 12 .

[0045] Example 3:

[0046] A preparation method of a Bi2Se3 / Sb2O3 / Si heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer is as follows: Clean the n-type silicon substrate, fix the mask on the silicon substrate, fix its surface downward in the sample area of the electron beam evaporation equipment, and turn on the electron beam evaporation equipment to prepare the Sb2O3 layer on the silicon surface. During the preparation process, the chamber vacuum is 10 -4 Pa, and the evaporation rate is about / s, with a time of 15 min, to obtain the Sb2O3 / Si heterojunction. Subsequently, using Bi2Se3 powder as the source, a Bi2Se3 thin film was prepared on the surface of the Sb2O3 layer by an electron beam evaporation device. During the preparation process, the vacuum degree in the chamber was 10 -4 Pa, and the evaporation rate was / s, with a time of 20 min, to obtain the Bi2Se3 / Sb2O3 / Si heterojunction. The sample was placed in a tube furnace for annealing treatment to improve the crystallization quality of the material. The annealing temperature was 250 °C, the annealing time was 60 min, and the annealing atmosphere was argon. A fixed electrode mask template was placed on the surface of the obtained Bi2Se3 / Sb2O3 / Si heterojunction. Using an electron beam evaporation device, a rectangular Ti / Au electrode was first prepared on the surface of the silicon substrate. The evaporation rate was / s. Ti and Au were evaporated successively, and the evaporation times were 15 min and 40 min respectively. Then, a rectangular Au electrode was prepared on the surface of the Bi2Se3 thin film. The evaporation rate was / s, and the evaporation time was 40 min. The distance between the two electrodes was 0.25 mm to obtain the Bi2Se3 / Sb2O3 / Si heterojunction photodetector.

Claims

1. A sandwich-type silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer, characterized in that The photodetector includes a silicon substrate, an Sb2O3 intermediate layer, a bismuth compound layer, and a pair of electrodes, and the pair of electrodes are respectively located on the surfaces of the silicon substrate and the bismuth compound layer.

2. The sandwich-type silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 1, characterized in that The silicon substrate is one of an n-type silicon substrate or a p-type silicon substrate.

3. The sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 1, characterized in that The thickness of the Sb2O3 intermediate layer is 5 nanometers to 1 micrometer.

4. The sandwich-type silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 1, wherein The bismuth compound layer is one of bismuth selenide or bismuth telluride thin films, and the thickness is less than 1 micrometer.

5. The sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 1, wherein Among the pair of electrodes, the electrode material located on the surface of the silicon substrate is one or any combination of several materials among Ti, Au, Ag, Cu, Pt, Al, Cr, In, graphene, and the thickness is less than 1 micrometer; the electrode material located on the surface of the bismuth compound layer is one or any combination of several materials among Ti, Au, Ag, Cu, Pt, Al, Cr, In, graphene, and the thickness is less than 1 micrometer; the electrode materials located on the surface of the silicon substrate and the surface of the bismuth compound layer are the same or different.

6. A method for preparing a sandwich silicon-based heterojunction self-powered broadband photodetector based on an Sb2O3 carrier blocking layer according to any one of claims 1-5, characterized in that The method includes the following steps: Step 1, clean the silicon substrate; Step 2, fix a mask on the silicon substrate to expose part of the silicon surface, and deposit an Sb2O3 layer on the exposed area of the silicon substrate by using an electron beam evaporation device; Step 3, prepare a bismuth compound layer on the surface of the Sb2O3 layer; Step 4, perform annealing treatment on the bismuth compound / Sb2O3 / silicon sandwich heterojunction to optimize the crystallization quality of the material; Step 5, prepare an electrode on the surface of the silicon substrate; Step 6, prepare an electrode on the surface of the bismuth compound.

7. The preparation method of the sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 6, characterized in that In the second step, when preparing the Sb2O3 layer by using an electron beam evaporation device, the vacuum degree is not higher than 10 -4 Pa, and the deposition rate is 8. The preparation method of the sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 6, characterized in that In the said Step 3, the bismuth compound layer is directly prepared on the surface of the Sb2O3 layer by electron beam evaporation, magnetron sputtering or chemical / physical vapor deposition method, or the bismuth compound thin film is transferred to the surface of the Sb2O3 layer.

9. The preparation method of the sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 6, characterized in that In the said Step 4, the annealing temperature is 150 - 300 °C, the annealing time is 10 - 360 minutes, and the annealing atmosphere is argon.

10. The preparation method of the sandwich silicon-based heterojunction self-powered broadband photodetector based on the Sb2O3 carrier blocking layer according to claim 6, characterized in that In the said Step 5 and Step 6, the electrode preparation method is electron beam evaporation, thermal evaporation, wet transfer or dry transfer.

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