Photoelectric detector based on silicon-tellurium composite structure and preparation method thereof

Abstract

The invention discloses a photoelectric detector based on a silicon-tellurium composite structure and a preparation method of the photoelectric detector, and belongs to the field of semiconductor optoelectronic devices.The photoelectric detector comprises a silicon substrate, a lower electrode, a tellurium material layer, a silicon dioxide layer and an upper electrode, the silicon dioxide layer is in contact connection with the upper end of the silicon substrate, the upper end of the silicon substrate is provided with a silicon hole, the tellurium material layer is located in the silicon hole, the tellurium material layer is directly in contact connection with the silicon substrate, the upper electrode is in contact connection with the upper end of the silicon dioxide layer, and the upper electrode is in contact connection with the tellurium material layer. According to the invention, tellurium materials with different morphologies grow in the silicon window, and heterojunction is formed by directly contacting the silicon substrate, so that the device has response in wave bands of 635 nm and 1550 nm, the device has dual-band detection performance, the response wavelength of the device is widened, and the response speed of the tellurium material prepared under an alkaline condition is fastest and can reach 0.3 s.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor optoelectronic devices, and in particular relates to a photoelectric detector based on a silicon-tellurium composite structure and a preparation method thereof. Background Art

[0002] A photodetector is a device that can convert light signals into electrical signals. It is mainly based on the photovoltaic effect of semiconductors. With the rapid development of wide-band detectors, more and more occasions require wide-band detection, such as wide-spectrum analysis, wide-band lidar, high-performance night vision, etc. Therefore, there is an urgent need to develop wide-spectrum photodetectors that cover both visible light and short-wave infrared. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a photodetector based on a silicon-tellurium composite structure and a preparation method thereof, wherein tellurium material is grown on a silicon substrate to form a heterojunction structure, and the prepared photodetector has dual-band detection performance.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] On the one hand, the present invention provides a photodetector based on a silicon-tellurium composite structure, comprising a silicon substrate, a lower electrode, a tellurium material layer, a silicon dioxide layer and an upper electrode, wherein the lower electrode is contact-connected to the lower end of the silicon substrate, the silicon dioxide layer is contact-connected to the upper end of the silicon substrate, the upper end of the silicon substrate has a silicon hole, the tellurium material layer is located in the silicon hole, the tellurium material layer is directly contact-connected to the silicon substrate, the upper electrode is contact-connected to the upper end of the silicon dioxide layer, and the upper electrode is contact-connected to the tellurium material layer.

[0006] Furthermore, the tellurium material layer is in a feather-like shape, a nanosheet-like shape or a nanorod-like shape.

[0007] Furthermore, the tellurium material layer has a thickness less than 500 nm.

[0008] On the other hand, the present invention also provides a method for preparing a photoelectric detector based on a silicon-tellurium composite structure, which is used to prepare the photoelectric detector based on the silicon-tellurium composite structure, and the preparation method comprises:

[0009] Prepare substrate: clean silicon wafers and cut them into preset sizes;

[0010] Gluing, exposure, and development: The silicon substrate is patterned through micro-nano processing technology, and the silicon hole pattern where the tellurium material is to be deposited is displayed through exposure;

[0011] Etching: Etching the developed silicon wafer;

[0012] Tellurium material deposition: depositing tellurium material on the etched silicon substrate;

[0013] Making electrodes: Patterning the silicon wafer, exposing and developing the corresponding electrode parts, and making the upper and lower electrodes.

[0014] Furthermore, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0015] A solution of 0.005-0.015 M tellurium dioxide and 0.5-1.5 M nitric acid is prepared as an acidic precursor solution of tellurium;

[0016] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0017] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

[0018] Furthermore, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0019] Prepare a solution of 0.005-0.015M tellurium dioxide and 0.5-1.5M nitric acid, and add ammonia water to the solution until the pH value of the solution is 7.5, as a neutral precursor solution of tellurium;

[0020] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0021] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

[0022] Furthermore, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0023] Dissolve 0.005-0.015 M tellurium dioxide and 0.03-0.07 M sodium hydroxide in ultrapure water as an alkaline precursor solution of tellurium;

[0024] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0025] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

[0026] Furthermore, the counter electrode is a platinum foil, and the reference electrode is a silver / silver chloride reference electrode.

[0027] Furthermore, the upper electrode and the lower electrode are obtained by using a magnetron sputtering method, first sputtering 5nm of chromium to improve adhesion, and then sputtering 50nm of gold.

[0028] Furthermore, the etching of the developed silicon wafer is specifically etching the developed silicon wafer using a reactive ion etcher.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention grows tellurium materials of different morphologies in the silicon window and forms a heterojunction by directly contacting the silicon substrate, so that the device responds in both the 635nm and 1550nm bands, has dual-band detection performance, broadens the wide device response wavelength, and the Te material prepared under alkaline conditions has the fastest response speed, which can reach 0.3s;

[0031] The present invention uses electrochemical deposition technology to prepare tellurium materials. This technology is green and efficient, has high sensitivity, is simple to operate, and has controllable growth conditions. The morphology of the tellurium material can be effectively controlled by controlling the deposition time.

[0032] The present invention uses a reactive ion etcher to perform micro-nano processing and etching on a silicon substrate to prepare a silicon micrometer hole array. This structure is conducive to secondary reflection of light and light absorption, and the etching method has a high selectivity and can be used on a large scale. By introducing a light trapping structure, light loss is reduced and absorption of incident light is enhanced.

[0033] The present invention adopts an electrochemical deposition method to grow tellurium material on a patterned silicon pore substrate, wherein the tellurium material includes various morphologies such as feather-like, nanosheet-like and nanorod-like, and is adjusted by the pH value of the precursor.

[0034] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0036] Figure 1 This is a schematic cross-sectional structure diagram of a photodetector based on a silicon-tellurium composite structure according to an embodiment of the present invention;

[0037] Figure 2 Scanning electron microscope images of tellurium materials and corresponding devices under different growth conditions of a photodetector based on a silicon-tellurium composite structure according to an embodiment of the present invention;

[0038] Figure 3This is a performance diagram of a photoelectric detector based on a silicon-tellurium composite structure under 1550nm laser irradiation according to an embodiment of the present invention;

[0039] Figure 4 This is a performance diagram of a photoelectric detector based on a silicon-tellurium composite structure under 635nm laser irradiation according to an embodiment of the present invention;

[0040] In the figure: 1. Gold lower electrode; 2. Silicon substrate; 3. Tellurium material layer; 4. Silicon dioxide layer; 5. Gold upper electrode. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0042] Figure 1 This is a schematic diagram of the cross-sectional structure of a photodetector based on a silicon-tellurium composite structure described in an embodiment of the present invention, wherein the photodetector includes a silicon substrate 2, a lower electrode, a tellurium material layer 3, a silicon dioxide layer 4 and an upper electrode, wherein the lower electrode is contact-connected to the lower end of the silicon substrate 2, the silicon dioxide layer 4 is contact-connected to the upper end of the silicon substrate 2, the upper end of the silicon substrate 2 has a silicon hole, the tellurium material layer 3 is located in the silicon hole, the tellurium material layer 3 is directly contact-connected to the silicon substrate 2, the upper electrode is contact-connected to the upper end of the silicon dioxide layer 4, and the upper electrode is contact-connected to the tellurium material layer 3.

[0043] Among many elements, tellurium (Te) is located between the non-metallic element Se and the metallic element Po, which determines that the properties of tellurium belong to semi-metal. It has higher metallic properties and stronger electronic reactivity than neighboring elements, a band gap of 0.32-1eV, a large specific surface area, good conductivity, high hole mobility, and surface plasmon resonance (LSPR) and other characteristics. These characteristics make tellurium materials very suitable for building wide-band photodetectors. In addition, silicon materials have low cost and mature preparation processes. PbS and Te materials with narrow bandgap widths are epitaxially grown on Si substrates to prepare silicon-based detectors, which can not only broaden the response band of silicon materials, but also effectively improve the device response speed and reduce dark current. The present invention grows tellurium materials of different morphologies in a silicon window, and forms a heterojunction by directly contacting the silicon substrate 2, so that the device responds in both the 635nm and 1550nm bands, has dual-band detection performance, and broadens the wide device response wavelength. The Te material prepared under alkaline conditions has the fastest response speed, which can reach 0.3s;

[0044] like Figure 1 As shown, the upper electrode and the lower electrode can be a gold upper electrode 5 and a gold lower electrode 1, respectively. According to different preparation methods, the tellurium material layer 3 is feather-shaped, nanosheet-shaped or nanorod-shaped. The tellurium material layer 3 has a thickness of less than 500 nm. The silicon pore can be formed by enclosing a silicon dioxide layer 4.

[0045] like Figure 2-4 As shown, an embodiment of the present invention further provides a method for preparing a photoelectric detector based on a silicon-tellurium composite structure, which is used to prepare the photoelectric detector based on the silicon-tellurium composite structure. The preparation method includes:

[0046] Prepare substrate: clean silicon wafers and cut them into preset sizes;

[0047] Gluing, exposure, and development: The silicon substrate 2 is patterned by micro-nano processing technology, and the silicon hole image where the tellurium material is to be deposited is displayed by exposure;

[0048] Etching: Etching the developed silicon wafer;

[0049] Tellurium material deposition: depositing tellurium material on the etched silicon substrate 2;

[0050] Making electrodes: Patterning the silicon wafer, exposing and developing the corresponding electrode parts, and making the upper and lower electrodes.

[0051] As a specific embodiment, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0052] A solution of 0.005-0.015 M tellurium dioxide and 0.5-1.5 M nitric acid is prepared as an acidic precursor solution of tellurium;

[0053] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0054] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, wherein the working electrode is a silicon substrate 2 after patterning.

[0055] As a specific embodiment, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0056] Prepare a solution of 0.005-0.015M tellurium dioxide and 0.5-1.5M nitric acid, and add ammonia water to the solution until the pH value of the solution is 7.5, as a neutral precursor solution of tellurium;

[0057] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0058] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, wherein the working electrode is a silicon substrate 2 after patterning.

[0059] As a specific embodiment, the tellurium material is deposited by electrochemical deposition, and the specific method is as follows:

[0060] Dissolve 0.005-0.015M tellurium dioxide and 0.03-0.07M sodium hydroxide in ultrapure water as the alkaline precursor solution of tellurium:

[0061] Quantitatively extracting the solution and adding it into an electrolytic cell;

[0062] Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, wherein the working electrode is a silicon substrate 2 after patterning.

[0063] As a specific embodiment, the counter electrode is a platinum foil, and the reference electrode is a silver / silver chloride reference electrode.

[0064] As a specific embodiment, the upper electrode and the lower electrode are obtained by using a magnetron sputtering method, first sputtering 5nm of chromium to improve adhesion, and then sputtering 50nm of gold.

[0065] As a specific embodiment, the etching of the developed silicon wafer is specifically etching the developed silicon wafer using a reactive ion etcher.

[0066] Next, the preparation method will be described in detail:

[0067] A method for preparing a photoelectric detector based on a silicon-tellurium composite structure comprises the following steps:

[0068] (1) Double-layer glue process

[0069] This embodiment uses a p-type doped Si / SiO2 substrate, which is prepared into a size of 1.5cm×1.5cm by a laser cutting machine, and is cleaned with acetone and anhydrous ethanol respectively, and the cleaning time is 15 minutes. Turn on the glue leveling machine switch, place the cleaned Si / SiO2 substrate on the turntable of the glue leveling machine and suck it, and evenly drip LOR photoresist with a glue-tipped dropper, and run according to the set program. The two speeds are: 500rpm, low-speed rotation for 5s, at this time the glue is thicker, and it is rotated again at a high speed of 1500rpm for 15s, so that the photoresist is evenly spread over the entire silicon wafer. After completion, turn on the glue drying machine, bake at 100℃ for 10min, and solidify the photoresist. After that, use the same speed and time to spin-coat AZ3100 photoresist and bake at 170℃ for 15min. The double-layer glue is more stable, which is conducive to subsequent etching processes.

[0070] (2) Exposure and development of silicon window pattern

[0071] Turn on the exposure machine, fix the mask, place the silicon wafer in the middle of the exposure machine, align it with the mask and press it, adjust the exposure time to 15s. Develop in AZ300 developer for 70s, start timing when the silicon wafer is placed in the developer, allow the developer to fully react with the photoresist, and the solution will appear pink after dissolution. Then rinse the residual photoresist on the surface with deionized water, blow dry with a nitrogen gun, and expose the silicon hole pattern.

[0072] (3) SiO2 etching process

[0073] Turn on the reactive ion etcher system, set the etching parameters, and introduce etching gas (sulfur hexafluoride SF6 + trifluoromethane CHF3) into the etching chamber. Set the RF power to 160W and etch for 30 minutes. At this time, a glow begins to appear in the etching chamber, and the patterned silicon dioxide layer 4 on the surface of the silicon wafer is being etched. After etching, acetone and AZ300 need to be used to remove the glue in turn to complete the preparation process of the silicon hole array. The silicon hole etching depth is 1μm-1.5μm.

[0074] (4) Growth of tellurium materials

[0075] Under acidic conditions, 0.01M tellurium dioxide (TeO2) powder is weighed and placed in a small amount of ultrapure water and magnetically stirred for 5 minutes. At this time, the powder is slightly soluble in water. 1M nitric acid (HNO3) is poured into it, and the powder quickly dissolves. The acidic precursor solution of Te is prepared.

[0076] Under neutral conditions, the precursor solution is still a 0.01MTeO2 and 1MHNO3 solution. Ammonia water is slowly added and measured in real time using a pH meter until the pH is adjusted to 7.5. At this time, the solution is slightly turbid, completing the preparation of the solution under neutral conditions.

[0077] Under alkaline conditions, sodium hydroxide (NaOH) is used as the main raw material, 0.01M TeO2 and 0.05M NaOH are dissolved in ultrapure water to make the solution pH = 12.5, which is recorded as the alkaline precursor solution of Te.

[0078] Use a measuring cylinder to take 100 ml of the above three solutions and add them to the electrolytic cell. In the electrochemical workstation, tellurium material is grown by constant potential deposition. The silicon hole substrate is used as the working electrode. The mode is set for cyclic voltammetry scanning. The scanning rate is set to 20mV / s. The position of the reduction peak in the curve is observed to explore the optimal deposition voltage. After scanning the cyclic voltammetry curve, -0.75V is used under acidic conditions, -0.85V is selected under neutral conditions, and -1.15V is used under alkaline conditions. The deposition time is 30s.

[0079] (5) Electrode preparation

[0080] The silicon wafer was exposed and patterned, and the corresponding electrode part was exposed by micro-nano processing technology. 5nm chromium and 50nm gold were magnetron sputtered on the upper and lower surfaces of the silicon substrate 2 respectively. Finally, it was soaked in acetone for 15 minutes to remove excess AZ3100 photoresist to complete the device preparation.

[0081] According to the above preparation method, the following can be obtained: Figure 1 A photodetector with a silicon-tellurium composite structure as shown.

[0082] refer to Figure 2 Scanning electron microscope images of tellurium materials and corresponding devices under different growth conditions. (a) and (d) show the feather-like and nanowire mixed structures under acidic conditions. At this time, the pH is the lowest, the reaction rate is too fast, and Te will rapidly nucleate and grow along the defects at the edge of the silicon hole. Figure 3 (b) and (e) are SEM images under neutral conditions, where the nanosheets are randomly distributed and thin. Figure 3 As shown in (c) and (f), the tiny nanorods evenly cover the entire silicon pore. By comparing the three forms, it can be observed that the morphology is most ideal under this condition.

[0083] refer to Figure 3 This is a performance diagram of a photodetector based on a silicon-tellurium composite structure under 1550nm laser irradiation in an embodiment of the present invention. After testing, a photodetector based on a silicon-tellurium composite structure obtained in this embodiment has an incident light wavelength of 1550nm, a laser power of 63mW, a detector photosensitive area of ​​110μm×110μm, and a spot area of ​​38mm2. When no bias is applied, the relevant performance diagram is obtained. The results show that the dark current is the smallest under acidic conditions, as low as 4.88×10-11A, the response curve stability is the best under neutral conditions, and the response speed is the fastest under alkaline conditions, which are 0.29s / 0.23s respectively. This conclusion proves that the performance of the photodetector is inseparable from the morphology of the semiconductor material.

[0084] Figure 4 This is a performance diagram of a photodetector based on a silicon-tellurium composite structure under 635nm laser irradiation in an embodiment of the present invention. The stable light response curve shows that the Si / Te photodetector responds to the 635nm laser. The specific detection rate under acidic conditions can reach 9.3×108Jones, and the response speed under alkaline conditions is still the fastest, with an average time of 0.3s.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A photodetector based on a silicon-tellurium composite structure, It is characterized in that It includes a silicon substrate, a lower electrode, a tellurium material layer, a silicon dioxide layer and an upper electrode, wherein the lower electrode is contact-connected to the lower end of the silicon substrate, the silicon dioxide layer is contact-connected to the upper end of the silicon substrate, the upper end of the silicon substrate has a silicon hole, the tellurium material layer is located in the silicon hole, the tellurium material layer is directly contact-connected to the silicon substrate, the upper electrode is contact-connected to the upper end of the silicon dioxide layer, and the upper electrode is contact-connected to the tellurium material layer.

2. The photodetector according to claim 1, It is characterized in that The tellurium material layer is in a feather shape, a nanosheet shape or a nanorod shape.

3. The photodetector according to claim 1 or 2, It is characterized in that The tellurium material layer has a thickness less than 500 nm.

4. A method for preparing a photodetector based on a silicon-tellurium composite structure, for preparing the photodetector based on a silicon-tellurium composite structure according to any one of claims 1 to 3, It is characterized in that The preparation method comprises: Prepare substrate: clean silicon wafers and cut them into preset sizes; Gluing, exposure, and development: The silicon substrate is patterned through micro-nano processing technology, and the silicon hole pattern where the tellurium material is to be deposited is displayed through exposure; Etching: Etching the developed silicon wafer; Tellurium material deposition: depositing tellurium material on the etched silicon substrate; Making electrodes: Patterning the silicon wafer, exposing and developing the corresponding electrode parts, and making the upper and lower electrodes.

5. The preparation method according to claim 4, It is characterized in that The tellurium material is deposited by electrochemical deposition, and the specific method is as follows: A solution of 0.005-0.015 M tellurium dioxide and 0.5-1.5 M nitric acid is prepared as an acidic precursor solution of tellurium; Quantitatively extracting the solution and adding it into an electrolytic cell; Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

6. The preparation method according to claim 4, It is characterized in that The tellurium material is deposited by electrochemical deposition, and the specific method is as follows: Prepare a solution of 0.005-0.015M tellurium dioxide and 0.5-1.5M nitric acid, and add ammonia water to the solution until the pH value of the solution is 7.5, as a neutral precursor solution of tellurium; Quantitatively extracting the solution and adding it into an electrolytic cell; Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

7. The preparation method according to claim 4, It is characterized in that The tellurium material is deposited by electrochemical deposition, and the specific method is as follows: Dissolve 0.005-0.015 M tellurium dioxide and 0.03-0.07 M sodium hydroxide in ultrapure water as an alkaline precursor solution of tellurium; Quantitatively extracting the solution and adding it into an electrolytic cell; Tellurium material growth is performed by constant potential deposition in a three-electrode electrochemical workstation, wherein the three-electrode electrochemical workstation comprises a working electrode, a counter electrode and a reference electrode, and the working electrode is a silicon substrate after etching a pattern.

8. The preparation method according to any one of claims 5 to 7, It is characterized in that The counter electrode is a platinum foil, and the reference electrode is a silver / silver chloride reference electrode.

9. The preparation method according to any one of claims 4 to 7, It is characterized in that The upper electrode and the lower electrode are obtained by a magnetron sputtering method, wherein 5 nm of chromium is firstly sputtered to improve adhesion, and then 50 nm of gold is sputtered.

10. The preparation method according to any one of claims 4 to 7, It is characterized in that The etching of the developed silicon wafer specifically involves etching the developed silicon wafer using a reactive ion etcher.

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