Photoelectric detector based on tellurium nanometer net and silicon heterojunction

Abstract

The invention discloses a photoelectric detector based on a tellurium nanometer net and a silicon heterojunction. The preparation method of the device comprises the following steps: exposing silicon in a region on a SiO2 / n-Si substrate by using photoetching and reactive ion etching processes, then manufacturing a gold top electrode by using processes such as thermal evaporation, and finally growing a tellurium nano net by using a vapor phase growth method to prepare the heterojunction photoelectric detector with a vertical structure. The limitation of chemical bonds on material synthesis and lattice mismatch heteroepitaxy is overcome through Van der Waals bonds between tellurium atom chains and spontaneous mismatch relaxation at a quasi Van der Waals interface, and the tellurium nanonet composed of self-welded tellurium nanowires transversely grows on the silicon surface at the low temperature of 100 DEG C. The preparation method has the advantages that the growth controllability of the one-dimensional tellurium nano material is good, the process is simple, the raw material cost is low, and the light response of the device is good.

Description

Technical Field

[0001] The present invention designs a photoelectric detector based on tellurium nanomesh and silicon heterojunction and related material growth method and device testing method. Specifically, tellurium nanowires obtained by low-temperature vapor phase growth are self-welded into a mesh, and the device has good junction effect and light response characteristics. Background Art

[0002] The successful preparation of graphene has opened a new era of two-dimensional materials. People's research on the material world has moved from three-dimensional materials to two-dimensional materials and one-dimensional materials. When the size of a substance reaches the nanometer level, its structure and the interaction between atoms will change greatly, resulting in small size effects, quantum size effects and quantum tunneling effects. One-dimensional materials have shown attractive prospects in the fields of nanoelectronic devices and spin devices due to their unique structure and physical and chemical properties.

[0003] There are currently many methods for synthesizing one-dimensional nanomaterials, the most common of which are arc discharge, chemical vapor deposition and template method. These methods require specific pressure, temperature, heating method, catalyst and matrix, etc.

[0004] Tellurium is an important one-dimensional material with excellent optical and electrical properties. Tellurium bulk materials are stacked together in a hexagonal array through interchain van der Waals forces. Two tellurium atoms in the chain are bonded by covalent bonds, and adjacent atomic chains are parallel to each other and bonded by weak bonds. The tellurium atomic chain presents a spiral asymmetric structure. The band gap of tellurium bulk materials is 0.31eV, and the band gap of a tellurium spiral single chain at room temperature is about 1.53eV.

[0005] At present, the most common methods for synthesizing tellurium nanowires are exfoliation, liquid phase synthesis, vapor phase growth, microwave synthesis in ionic liquids, biomolecule-assisted method, and chemical vapor deposition method. The present invention adopts the vapor phase growth method, and can synthesize wafer-level self-welded tellurium nanonets at only 100°C. Through the spontaneous mismatch relaxation at the van der Waals bonds and quasi-van der Waals interfaces between tellurium atomic chains, the tellurium nanonets can grow laterally on any surface, including rigid substrates, flexible substrates, and layered material surfaces. The present invention selects silicon as the growth substrate, bypassing the limitations of semiconductor material synthesis and lattice mismatch heterogeneous integration, and demonstrates a heterojunction photodetector of tellurium nanonets and silicon grown in a bottom-up manner. Summary of the invention

[0006] This patent provides a photodetector based on tellurium nanomesh and silicon heterojunction. The detector grows tellurium nanomesh at low temperature and normal pressure, does not require metal catalysis, has smaller composite defects at the heterojunction interface, and improves the device's responsiveness.

[0007] The structure of the detector is:

[0008] (1) n-type Si substrate with SiO2 oxide layer;

[0009] (2) Etching the oxide layer in one area and exposing the Si underneath;

[0010] (3) making gold electrodes around the etched area of ​​the substrate;

[0011] (4) Growing a tellurium nanomesh on the etched area.

[0012] In the above (1), the substrate is selected as SiO2 (100nm-300nm) / n-Si (orientation 100, resistivity 1-10Ω·cm);

[0013] The etching area of ​​the substrate in (2) has a size of 30 μm×30 μm to 5 mm×5 mm;

[0014] The electrode materials in (3) are chromium and gold, and the evaporation thicknesses are 10 nm and 50 nm respectively;

[0015] The (4) method grows tellurium nano-mesh in a dual-temperature zone tubular furnace, using inert gas argon as carrier gas, with a carrier gas flow rate of 10sccm-15sccm, a heating temperature zone of 430°C to 480°C, and a growth temperature zone of 80°C to 200°C.

[0016] This patent provides a photodetector based on tellurium nanonet and silicon heterojunction, the preparation steps are as follows:

[0017] (1) Slicing the growth substrate into required specifications and performing surface cleaning;

[0018] (2) Opening windows on the growth substrate;

[0019] (3) Evaporation of electrodes on the etched growth substrate

[0020] (4) Place tellurium powder in a quartz boat and push it into the heating zone of a tube furnace. Push the substrate into the growth zone with the polished surface facing upward. The carrier gas enters from one end of the quartz tube and is discharged from the other end.

[0021] (5) The quartz tube is kept at atmospheric pressure;

[0022] (6) During the vapor phase growth process, an inert gas is used as a carrier gas, and the temperature at the center of the tube furnace is set according to the time period as follows: the temperature is divided into three stages, the first stage is the heating stage, the second stage is the growth stage, and the third stage is the natural cooling stage.

[0023] Preferably, the substrate in step (1) is SiO2 (300 nm) / n-Si (orientation 100, resistivity 1-10 Ω·cm), and the substrate is cleaned by ultrasonic cleaning with acetone, anhydrous ethanol and deionized water in sequence, with the ultrasonic time being 300 s and the ultrasonic power set to 60 W.

[0024] Preferably, in step (2), the substrate is spin-coated with AR-P 5350 photoresist at 4000 r / min, baked on a constant temperature table at 100° C. for 4 min, and the photoresist is patterned using laser maskless lithography technology of a digital micromirror chip. The sample is then placed in a developer for 40 s to expose the patterned SiO2 surface, with a window size of 5 mm×5 mm. Reactive ion etching is used, and carbon tetrafluoride and argon are used as process gases with gas flow rates of 200 sccm and 100 sccm, respectively. The etching power is set to 100 W, and the etching time is 360 s to obtain exposed Si holes. The sample is immersed in an acetone solution for 5 min to remove the photoresist, and then rinsed with alcohol and deionized water and blown dry with a nitrogen gun. The substrate is then placed on a constant temperature table at 120° C. and baked for 20 min to remove surface moisture.

[0025] Preferably, in step (3), the etched substrate is again spin-coated with photoresist and patterned by photolithography, and the electrode materials are chromium and gold, and a vacuum thermal evaporation machine is used at a vacuum degree of 5×10 -5 The evaporation was performed below pa, and the evaporation thickness was 10nm and 50nm respectively.

[0026] Preferably, in step (4), the distance between the growth substrate and the quartz boat containing tellurium powder is 8 cm-10 cm.

[0027] Preferably, in step (5), the atmospheric state needs to be maintained after the quartz tube is cleaned with inert gas for 30 minutes, with a gas flow rate of 200 sccm-300 sccm.

[0028] Preferably, the carrier gas in step (6) is argon, and the carrier gas flow rate is 10 sccm-15 sccm.

[0029] Preferably, in step (6), in the first stage, the temperature is set to heat the heating zone of the tubular furnace to 450°C at a heating rate of 15°C-20°C / min, and the growth zone of the tubular furnace is heated to 100°C at a heating rate of 15°C-20°C / min; in the second stage, the temperature is set to maintain the heating zone at 450°C for 14 hours and the growth zone at 100°C for 16 hours; in the third stage, the temperature of the heating zone is naturally cooled from 450°C to below 30°C, and the temperature of the growth zone is naturally cooled from 100°C to below 30°C, and the cover of the tubular furnace can be opened.

[0030] The growth substrates include: SiO2 / Si with different resistance, oxide layer thickness and doping type.

[0031] The advantages of this patent are:

[0032] (1) The entire growth process of the nanomesh is under atmospheric pressure, which inhibits the evaporation of raw materials and produces a nanomesh with uniform morphology; (2) The nanomesh can be grown on various types of surfaces without worrying about the incompatibility of heterogeneous integration; (3) The growth of the nanomesh is spontaneous, does not require metal catalysis, and does not have to consider complex epitaxial relationships; (4) The tellurium nanomesh undergoes self-welding during its growth process, and compared with the nanomesh obtained by liquid phase deposition, the junction resistance is lower and the mechanical robustness is better. (5) The material obtained by in-situ growth reduces defects at the interface and improves the responsiveness of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The device structure diagram of the present invention is shown in FIG. 1 : silicon dioxide; 2 : tellurium nanonet; 3 : electrode; 4 : silicon.

[0034] Figure 2 This is a diagram of the experimental device for preparing tellurium nanonets according to the present invention. In it, 1 is an air inlet; 2 is a dual-temperature zone tubular furnace; 3 is a refractory brick; 4 is an air outlet; 5 is tellurium powder; 6 is a growth substrate; and 7 is a one-inch quartz tube.

[0035] Figure 3 (a) is an image of the sample prepared in Example 1.

[0036] Figure 3 (b) is an image of the sample prepared in Example 2.

[0037] Figure 4 is the Raman spectrum in Example 1.

[0038] Figure 5 is a scanning electron microscope image in Example 1.

[0039] Figure 6 is the IV curve of Example 2 under dark conditions.

[0040] Figure 7 It is the IT curve and responsivity of different wavelengths in Example 2. DETAILED DESCRIPTION

[0041] The specific implementation modes of the present invention are described below to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0042] Implementation examples:

[0043] The method for cleaning the substrate in the specific implementation example is as follows: (1) Take out a wafer-level (100) oriented SiO2 / n-Si substrate from the glove box, cut it into square substrates of 1.5 cm×1.5 cm, and place it in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning, with the ultrasonic time being 300 s and the ultrasonic power set to 60 W. Finally, use tweezers to clamp the substrate out of the deionized water, blow dry the water vapor on the substrate in one direction with a nitrogen gun, and place it in a culture dish.

[0044] Implementation Example 1:

[0045] Place a quartz tube with a diameter of one inch and a length of about 120 cm on a dual-temperature zone tube furnace, weigh 1 g of tellurium powder in a quartz boat, and push the quartz boat into the quartz tube (refer to Figure 2 Place the cleaned substrate in the quartz tube (reference Figure 2 Position 6). Figure 2 A refractory brick is added at position 3, and the upstream of the quartz tube is connected to the carrier gas and the downstream is connected to the vacuum pump.

[0046] Turn on the vacuum pump and draw the vacuum degree in the quartz tube to below 3Pa. Keep it for 30 minutes and then turn it off. Turn on the flowmeter and set the argon flow rate to 200sccm to restore the vacuum degree in the quartz tube to the atmospheric state. Connect the downstream to the exhaust gas collection device and keep it for another 10 minutes. Set the argon flow rate to 15sccm.

[0047] The first stage of growth sets the heating temperature zone of the tube furnace (reference Figure 2 The temperature of position 5) is raised to 450°C at a heating rate of 15°C / min, and the growth temperature zone of the tube furnace is set (reference Figure 2 The temperature at position 6) is increased to 100°C at a heating rate of 20°C / min; in the second stage of growth, the temperature of the heating zone of the tubular furnace is set to 450°C and maintained for 14 hours, and the temperature of the growth zone of the tubular furnace is set to 100°C and maintained for 16 hours; the third stage of growth is natural cooling to room temperature.

[0048] After preparation, take out the sample for testing.

[0049] Figure 3 (a) is the prepared sample image;

[0050] Figure 4 To prepare the Raman spectra of the samples;

[0051] Figure 5Scanning electron microscope images of the prepared samples show that as the growth time increases, the tellurium nanowires extend to connect with each other, and there is obvious self-welding at the junctions between the wires. The diameter of the tellurium nanowires is 100nm to 200nm, and the length is 3μm to 8μm.

[0052] The results show that the tellurium nanowires grown in situ at low temperature and normal pressure provided by this patent have good crystallinity, the growth of the tellurium nanowires along the c-axis is more favorable, and spontaneous steam condensation occurs during the growth process, forming welding points in the contact area between the nanowires, allowing the tellurium nanowires to self-weld into a network.

[0053] Implementation Example 2:

[0054] The cleaned substrate was placed on a spinner, AR-P 5350 photoresist was spin-coated at 4000 r / min, and baked on a 100°C constant temperature table for 4 min. The photoresist was patterned using laser maskless lithography of a digital micromirror chip. The sample was then placed in a developer for 40 s to expose the patterned SiO2 surface. The window size was 5 mm × 5 mm. Reactive ion etching was used, with carbon tetrafluoride and argon as process gases. The gas flow rates were 200 sccm and 100 sccm, respectively. The etching power was set to 100 W, and the etching time was 360 s to obtain exposed Si holes (reference Figure 1 ), soak the sample in acetone solution for 5 minutes to remove the photoresist, then rinse it with alcohol and deionized water and blow it dry with a nitrogen gun, and then bake the substrate on a 120℃ constant temperature table for 20 minutes to remove the water vapor on the surface.

[0055] The etched substrate was placed on a spinner, AR-P 5350 photoresist was spin-coated at 4000 r / min, and baked on a 100°C constant temperature table for 4 min. The photoresist was patterned using laser maskless lithography technology of a digital micromirror chip (refer to Figure 1 ), and then placed the sample in a developer for 40 seconds. The electrode materials were chromium and gold. A vacuum thermal evaporation machine was used at a vacuum degree of 5×10 -5 The evaporation was performed below pa, and the evaporation thickness was 10nm and 50nm respectively.

[0056] Place a quartz tube with a diameter of one inch and a length of about 120 cm on a dual-temperature zone tube furnace, weigh 1 g of tellurium powder in a quartz boat, and push the quartz boat into the quartz tube (refer to Figure 2 Place the cleaned substrate in the quartz tube (reference Figure 2 Position 6). Figure 2 A refractory brick is added at position 3, and the upstream of the quartz tube is connected to the carrier gas and the downstream is connected to the vacuum pump.

[0057] Turn on the vacuum pump and draw the vacuum degree in the quartz tube to below 3Pa. Keep it for 30 minutes and then turn it off. Turn on the flowmeter and set the argon flow rate to 200sccm to restore the vacuum degree in the quartz tube to the atmospheric state. Connect the downstream to the exhaust gas collection device and keep it for another 10 minutes. Set the argon flow rate to 15sccm.

[0058] The first stage of growth sets the heating temperature zone of the tube furnace (reference Figure 2 The temperature of position 5) is raised to 450°C at a heating rate of 15°C / min, and the growth temperature zone of the tube furnace is set (reference Figure 2 The temperature at position 6) is increased to 100°C at a heating rate of 20°C / min; in the second stage of growth, the temperature of the heating zone of the tubular furnace is set to 450°C and maintained for 14 hours, and the temperature of the growth zone of the tubular furnace is set to 100°C and maintained for 16 hours; the third stage of growth is natural cooling to room temperature.

[0059] After preparation, take out the sample for testing.

[0060] Figure 3 (b) is the prepared sample image; Figure 6 is the IV curve of the prepared sample under dark conditions; Figure 7 It is the different wavelength responsivity and IT curve of the prepared samples.

[0061] The results show that the tellurium nanomesh and silicon heterojunction provided by this patent has an obvious junction effect and a wide spectral response of 365nm-980nm.

Claims

1. A photodetector based on tellurium nanomesh and silicon heterojunction, characterized by: The structure of the detector is: (1) n-type Si substrate with SiO2 oxide layer; (2) Etching the oxide layer in one area and exposing the Si underneath; (3) making gold electrodes around the etched area of ​​the substrate; (4) Growing a tellurium nanomesh on the etched area.

2. The photodetector based on tellurium nanomesh and silicon heterojunction according to claim 1 is characterized in that: (1) the substrate is selected from SiO2 (100nm-300nm) / n-Si (orientation 100, resistivity 1-10Ω·cm).

3. The photodetector based on tellurium nanomesh and silicon heterojunction according to claim 1, characterized in that: (2) The etching area size of the substrate is 30μm×30μm to 5mm×5mm.

4. The photodetector based on tellurium nanomesh and silicon heterojunction according to claim 1, characterized in that: (3) The electrode materials selected are chromium and gold, and the vapor deposition thickness is 10nm and 50nm respectively.

5. The photodetector based on tellurium nanomesh and silicon heterojunction according to claim 1, characterized in that: (4) The tellurium nanomesh was grown in a dual-temperature zone tubular furnace, with inert argon as carrier gas, a carrier gas flow rate of 10 sccm-15 sccm, a heating temperature zone of 430°C to 480°C, and a growth temperature zone of 80°C to 200°C.

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