A bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction, its fabrication method, and its application.
Patent Information
- Application Number
- CN202610763293.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-29
- Publication Date
- 2026-09-01
AI Technical Summary
二者构建Ⅱ型范德华异质结可实现光生载流子高效分离，但现有GeS1-xSex基异质结器件尚未实现栅压调控双向光电流与高偏振灵敏度的一体化集成，存在响应度低、偏振比小功耗高等缺陷
1.本发明基于六方氮化硼/硫硒化亚锗/二硫化钨异质结的光电晶体管具有正负栅压调控，光电性能优异等特点；采用三元合金GeSxSey（x=0.2~0.4，y=0.6~0.8）纳米片与半导体相WS2纳米片结合，实现独特的外加栅压调控传输特性，在635 nm下实现了良好的光电响应性能，具有新型的范德瓦尔斯异质结光电晶体管结构。
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Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of two-dimensional semiconductor optoelectronic devices, specifically, it relates to a device based on hexagonal boron nitride / germanium sulfoselenide / tungsten disulfide (h-BN / GeS). x Se y Bidirectional polarization phototransistor of heterojunction / WS2, its fabrication method and application. Background Technology
[0002] Optical information is a crucial medium for information acquisition, and humans primarily acquire and utilize optical signals through photodetectors. Photodetectors are optoelectronic devices that convert optical signals into electrical signals based on principles such as photoconductivity and photovoltaics. During this conversion, photodetectors can identify information at different wavelengths and optical powers. This property makes photodetectors widely applicable in fields such as image recognition and encryption. However, traditional photodetectors suffer from significant inherent noise defects, low polarization detection resolution, and limited integration capabilities. Therefore, novel two-dimensional semiconductor materials have emerged, providing new options for high-performance, ultra-sensitive, wide-bandwidth, and miniaturized photodetectors. Furthermore, the tunable bandgap and nanometer-scale thickness of two-dimensional layered semiconductors make miniaturized integration of these devices possible.
[0003] Reconfigurable transistors typically refer to transistors that can electrostatically control polarity and bidirectional photocurrent through gate voltage. Among these, two-dimensional phototransistors with bidirectional photoresponse have gradually become a research hotspot in recent years. Wang constructed a semi-floating gate programmable photovoltaic photodetector based on WSe2 / h-BN / graphene. By controlling the gate voltage pulse, opposite built-in electric field junctions can be formed in the device, achieving non-volatile reversible switching between positive and negative photoresponse. Polarization photodetectors are a type of optoelectronic device that can simultaneously sense light intensity and polarization direction. Their core function lies in sensing the material or structural characteristics. The main working principle of this type of detector is based on the anisotropy of two-dimensional materials, that is, the absorption of light at different polarization angles varies. When incident light shines on a polarizer at a fixed angle, since natural light is unpolarized, its electric field vibration vector is uniformly and randomly distributed in a plane perpendicular to the direction of light propagation, without a dominant vibration orientation. The filtering and screening effect of polarizers on light is essentially due to the anisotropy and dichroism of the material itself. Compared with traditional photodetectors, polarizers can capture surface roughness and material anisotropy of target objects, which traditional photodetectors cannot do, greatly enriching the information dimensions of photodetectors.
[0004] Group IV-VI germanium sulfoselenide (GeS) 1-x Se xThe ternary alloy is a p-type two-dimensional semiconductor, and its band gap and in-plane anisotropy can be continuously tuned through the S / Se composition; WS2 is a typical n-type transition metal sulfide, possessing high electron mobility and layer-dependent band gap characteristics. The two can be used to construct a type II van der Waals heterojunction to achieve efficient separation of photogenerated carriers, but existing GeS2... 1-x Se x The heterojunction device has not yet achieved the integrated combination of gate voltage-controlled bidirectional photocurrent and high polarization sensitivity, and has defects such as low responsivity, small polarization ratio and high power consumption. Summary of the Invention
[0005] In view of the technical problems existing in the prior art, and in order to overcome the shortcomings and disadvantages of the prior art, the primary objective of the present invention is to provide a bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction.
[0006] Another objective of this invention is to provide a method for fabricating the aforementioned bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction. This method achieves self-driven bidirectional photoresponse and high-performance polarization detection simultaneously through alloy engineering and gate voltage bandgap modulation.
[0007] Another object of the present invention is to provide the application of the above-mentioned bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction.
[0008] The objective of this invention is achieved through the following technical solution: A bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction includes a SiO2 / Si substrate and h-BN / GeS x Se y / WS2 heterojunction and electrodes, wherein the heterojunction is composed of h-BN, GeS x Se y Nanosheets and WS2 nanosheets overlap to form GeS x Se y In the model, x = 0.2~0.4, y = 0.6~0.8, and h-BN is a hexagonal boron nitride insulating layer; respectively, in non-overlapping GeS... x Se y Au electrodes were deposited on nanosheets and WS2 nanosheets and then annealed at 150-200°C under a protective gas atmosphere.
[0009] Preferably, the thickness of the Au electrode is 30-70 nm; the protective gas is nitrogen or argon; and the annealing time is 30-60 min.
[0010] Preferably, the GeS x Se yThe nanosheets have a thickness of 40-50 nm and a lateral dimension of 20-40 μm; the WS2 nanosheets have a thickness of 25-30 nm; and the h-BN has a thickness of 5-10 nm.
[0011] Preferably, the GeS x Se y The nanosheets are grown on a substrate using a low-pressure rapid physical vapor deposition method and obtained by mechanical pressing; the WS2 nanosheets are obtained on a cleaned SiO2 / Si substrate by mechanical exfoliation.
[0012] The method for fabricating a bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfoselenide / tungsten disulfide heterojunction includes the following specific steps: S1. GeS2 grown on SiO2 / Si substrate using low-pressure rapid physical vapor deposition. x Se y Nanosheets were mechanically pressed and transferred to a SiO2 / Si substrate using PDMS, and then the bright yellow GeS2 nanosheets were selected using an optical microscope. x Se y Nanosheets; S2. WS2 nanosheets were obtained on a cleaned SiO2 / Si substrate by mechanical exfoliation. The sample surface was removed by immersion in anhydrous ethanol to remove adhesive residue. The yellow-green WS2 nanosheets were selected by optical microscopy. S3. h-BN was deposited as an insulating layer on a SiO2 / Si substrate using a dry transfer method; WS2 nanosheets were transferred to GeS2 substrate using a dry transfer method. x Se y h-BN / GeS was prepared by first annealing on nanosheets at 100–150 °C under a protective gas atmosphere. x Se y / WS2 vertical heterojunction; S4. Using ultraviolet lithography, WS2 nanosheets and GeS2 nanosheets were fabricated. x Se y The source and drain electrodes were developed by photolithography on the nanosheet, and Au electrodes were deposited by electron beam evaporation. After the photoresist was dissolved by immersion in acetone, the fabricated device was subjected to a second annealing at 150-200°C to obtain the h-BN / GeS2 nanosheet based device. x Se y / WS2 heterojunction bidirectional polarization phototransistor.
[0013] Preferably, the first annealing time in step S3 is 30-60 min, the protective gas in step S4 is nitrogen or argon, and the second annealing time is 30-60 min.
[0014] The application of the bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction in the field of optoelectronic devices for encrypted-decrypted information transmission.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention relates to a phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction, which features positive and negative gate voltage control and excellent photoelectric performance; it employs a ternary alloy GeS1... x Se y By combining (x=0.2~0.4, y=0.6~0.8) nanosheets with semiconductor phase WS2 nanosheets, unique external gate voltage-controlled transmission characteristics are achieved, resulting in good photoelectric response performance at 635 nm, and a novel van der Waals heterojunction phototransistor structure.
[0016] 2. This invention uses an alloying process to prepare GeS from GeSe and GeS. x Se y The characteristics of (x=0.2~0.4, y=0.6~0.8) nanosheets and fixed band structure solve the problem of GeS x Se y Scientific issues such as the effective light absorption efficiency of nanosheets (x=0.2~0.4, y=0.6~0.8) and the large noise current of WS2 nanosheets.
[0017] 3. The GeS of the present invention x Se y Nanosheets possess unique polarization sensitivity and high carrier mobility, while also effectively suppressing deep-level defects in germanium sulfide and germanium selenide, reducing the nonradiative recombination lifetime of carriers, and shortening the photoresponse time.
[0018] 4. This invention is based on hexagonal boron nitride / germanium sulfoselenide (GeS). x Se y The phototransistor with a tungsten disulfide heterojunction (x=0.2~0.4, y=0.6~0.8) exhibits a bidirectional photoresponse. Here, germanium sulfide selenide is a GeS... 0.2 Se 0.8 Best performance (V) G =60 V and 0 V exhibit negative photocurrent, V G =-60 V exhibits positive photocurrent) Self-driven photoelectric performance (under 635 nm illumination, the maximum photoresponse with a positive gate voltage is -600.82 mA / W, with rise and fall times of 8 / 10 ms; with a negative gate voltage, the maximum photoresponse is 131.74 mA / W, with rise and fall times of 6 / 7 ms). Furthermore, based on h-BN / GeS 0.2 Se 0.8The / WS2 heterojunction phototransistor exhibits a dichroic color ratio of 1.18 under 635 nm illumination and displays a bidirectional polarization response (V0). G The maximum polarization ratio is 17.4 at 60 V. G The maximum polarization ratio is 11 at -60 V.
[0019] 5. In the bidirectional polarization phototransistor of the present invention, the heterojunction is formed by transferring WS2 onto germanium sulfide selenide. By applying a gate voltage on the SiO2 / Si substrate to control the Fermi level position of WS2, the potential difference formed by the two materials after applying the gate voltage leads to the polarity reversal of the photocurrent, realizing a unique gate-controlled bandgap contact capability. The bidirectional polarization response with polarity reversal is realized by utilizing the polarization characteristics of the materials themselves. Based on this, it can be used in the field of optoelectronic devices for information transmission such as encryption and decryption. Attached Figure Description
[0020] Figure 1 Example 1 is based on h-BN / GeS 0.2 Se 0.8 A schematic diagram of the bidirectional polarization phototransistor of the / WS2 heterojunction; Figure 2 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Optical microscope image of a bidirectional polarization phototransistor with a / WS2 heterojunction; Figure 3 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Current-voltage curves of a bidirectional polarization phototransistor with a WS2 heterojunction under different gate voltages; Figure 4 Example 1 is based on h-BN / GeS 0.2 Se 0.8 The relationship between photoresponsivity and optical power density of a bidirectional polarization phototransistor with a WS2 heterojunction under different gate voltages; Figure 5 Example 1 is based on h-BN / GeS 0.2 Se 0.8 The heterojunction polarization absorption spectrum of the bidirectional polarization phototransistor of the / WS2 heterojunction. Figure 6 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Polar plot of the polarization absorption spectrum of the heterojunction bidirectional polarization phototransistor of / WS2 heterojunction; Figure 7 Example 1 is based on h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G =Current-time curve at 60V gate voltage; Figure 8 Example 1 is based on h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G Current-time curve at -60V gate voltage; Figure 9 Example 1 is based on h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G =Polar coordinate diagram of photocurrent under 60V gate voltage; Figure 10 Example 1 is based on h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G Polar plot of photocurrent at a gate voltage of -60 V; Figure 11 Example 2 is based on h-BN / GeS 0.4 Se 0.6 The relationship between photoresponsivity and optical power density of a bidirectional polarization phototransistor with a WS2 heterojunction under different gate voltages; Figure 12 Example 4 is based on h-BN / GeS 0.2 Se 0.8 A comparison of the voltage-current relationship between the bidirectional polarization phototransistor of the WS2 heterojunction before annealing and the phototransistor of Example 1 after annealing. Figure 13 The graph shows the relationship between photoresponsivity and photopower density of the h-BN / GeSe / WS2 heterojunction-based transistor in Comparative Example 1 under different gate voltages. Detailed Implementation
[0021] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. The described embodiments are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from publicly available commercial channels.
[0022] Example 1
[0023] 1. A 2-inch SiO2 / Si wafer was cleaved along the lattice orientation to divide a single wafer into uniform 2 cm × 1 cm substrates. GeS powder (8.3 mg) and GeSe powder (41.7 mg) in a molar ratio of 13:19 were poured into a quartz boat, thoroughly mixed, and spread evenly according to the substrate size. The 2 cm × 1 cm SiO2 / Si substrate was placed at an angle in the center of the quartz boat. Finally, the quartz boat was smoothly pushed into the central heating region of a sliding tube furnace for growth, with the internal pressure fixed at -0.1 MPa (approximately 10 Torr). The temperature of the quartz tube was set to 570 °C, with a heating rate maintained at 20-25 °C / min. After reaching the set temperature, the heating area was moved to the area of the quartz boat and held for 4 min. After holding, the furnace was removed, and the sample was removed from the quartz boat after cooling to room temperature. The GeS sample was observed under an optical microscope. 0.2 Se 0.8 Whether the nanosheets grew vertically was determined by microscopic observation after cooling at room temperature; numerous yellow, sheet-like samples were observed. GeS2 nanosheets with a thickness of 40-50 nm and a lateral dimension of 20-50 μm were selected. 0.2 Se 0.8 Nanosheets; 2. A 2-inch SiO2 / Si wafer was cleaved according to the substrate's lattice orientation, dividing the entire wafer into 1 cm × 1 cm uniform substrates. These substrates were then ultrasonically cleaned with anhydrous ethanol and deionized water for 5-10 minutes to obtain clean SiO2 / Si substrates. The three-dimensional transfer platform was heated to 40°C, and the transfer environment was maintained. h-BN and GeS2 were then transferred... 0.2 Se 0.8 Nanosheets and WS2 nanosheets were stacked sequentially, and the three-dimensional transfer platform was heated to 60°C and held for 20 min to enhance the contact effect between the layers of the heterojunction. Residual adhesive was removed by immersion in an ethanol solution for 15 min to obtain h-BN / GeS2 nanosheets. 0.2 Se 0.8 / WS2 heterojunction; 3. In h-BN / GeS 0.2 Se 0.8 On the / WS2 heterojunction, the photoresist was uniformly spin-coated at 4000 rpm / min for 60s using a spin coater, followed by dark treatment on a 100℃ heating stage for 4min. The electrode was then photolithographically etched using a photolithography machine. Finally, the SiO2 / Si was immersed in the developer for 20s to remove the laser-irradiated part. The integrity of the material on the substrate and whether the electrode pattern was successfully developed were observed under an optical microscope.
[0024] 4. A 50nm Au electrode was deposited using an electron beam evaporation deposition system. The phototransistor was then removed and immersed in acetone for 5 minutes. After the photoresist dissolved, gold removal was performed to obtain a substrate with the electrode. The phototransistor was then annealed at 150°C for 30 minutes in a glove box or annealing furnace under vacuum argon to improve the contact quality between the electrode and the material, remove small molecule impurities between the electrode and the semiconductor material, thereby reducing the contact barrier and obtaining GeS. 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor.
[0025] Figure 1 Example 1 is based on h-BN / GeS 0.2 Se 0.8 A schematic diagram of the bidirectional polarization phototransistor of the / WS2 heterojunction, GeS 0.2 Se 0.8 The atomic ratio of sulfur to selenium in the nanosheets is 1:4. Figure 1 It can be seen that some GeS 0.2 Se 0.8 Nanosheets overlap with WS2 nanosheets to form h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction, Au electrodes are located on non-overlapping GeS 0.2 Se 0.8 On nanosheets and WS2 nanosheets. Figure 2 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Optical microscope image of a bidirectional polarization phototransistor with a / WS2 heterojunction. Figure 2 It can be seen that white represents GeS. 0.2 Se 0.8 Nanosheets, yellow is WS2 nanosheet, blue is insulating layer h-BN, source electrode (S) is connected to WS2 nanosheet, drain electrode (D) is connected to GeS 0.2 Se 0.8 On a nanosheet. The current ratio of this phototransistor at a bias voltage of -1V to that at a bias voltage of 1V is 10. 2 This indicates that the PN type h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction exhibits flow-regulating behavior. Figure 3 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Current-voltage curves of a bidirectional polarization phototransistor with a / WS2 heterojunction under different gate voltages. Figure 3 From this, we can see that h-BN / GeS 0.2 Se 0.8The / WS2 heterojunction phototransistor exhibits both photoelectric and photovoltaic effects under 635 nm incident light irradiation. Tests were conducted under zero source-drain bias and 635 nm laser irradiation. The curves show significant gate-voltage dependent photovoltaic characteristics, with the photocurrent polarity reversibly switching with positive and negative gate voltage adjustment. This demonstrates the dynamic control mechanism of the gate voltage on the heterojunction's built-in electric field, confirming the core characteristic of the phototransistor's self-driven bidirectional photoresponse without external bias. Under 635 nm irradiation, the phototransistor achieves gate-voltage controlled bidirectional photoresponse. It can be observed that under positive gate voltage, with increasing gate voltage and considering the phototransistor's IV curve, the short-circuit current (Io) increases. sc With the increase of ), and under the condition of negative gate voltage, as the negative gate voltage decreases, the positive short-circuit current (I) increases. sc ) also increases accordingly. In V G The open-circuit voltage of the phototransistor at -60 V (V) oc ) and short-circuit current (I sc The values reached -0.37 V and 0.45 nA respectively; at V G =60 V Open-circuit voltage of the phototransistor (V oc ) and short-circuit current (I sc The open-circuit voltages and short-circuit currents reached 0.51 V and -2.22 nA, respectively. The positive and negative open-circuit voltages and short-circuit currents indicate that the heterojunction achieved polarity reversal under different gate voltages, thus obtaining the bidirectional photocurrent phenomenon. Figure 4 Example 1 is based on h-BN / GeS 0.2 Se 0.8 The optical responsivity and optical power density relationship curves of the / WS2 heterojunction bidirectional polarization phototransistor under different gate voltages are derived from... Figure 4 It can be seen that the photoresponsivity of the phototransistor always exhibits a monotonically decreasing trend under different gate voltages, and the photoresponsivity decays sublinearly with increasing incident light power, which is due to the enhanced Auger recombination of photogenerated carriers under high light power. The responsivity shows an order of magnitude difference under positive and negative gate voltages, which quantitatively reflects the regulatory effect of gate voltage on photoelectric conversion efficiency, indicating that the h-BN / GeS... 0.2 Se 0.8 The / WS2 heterojunction phototransistor has high-sensitivity photodetection performance.
[0026] Figure 5 Example 1 is based on h-BN / GeS 0.2 Se 0.8 The heterojunction polarization absorption spectrum of the / WS2 heterojunction bidirectional polarization phototransistor, by Figure 5 It can be seen that the difference in absorption of linearly polarized light in different directions by the phototransistor is called dichroism, indicating that h-BN / GeS 0.2 Se 0.8 Orientation and anisotropy of the microstructure of / WS2 heterojunction. Figure 6 Example 1 is based on h-BN / GeS 0.2 Se 0.8 Polar coordinates of the heterojunction polarization absorption spectrum of the / WS2 heterojunction bidirectional polarization phototransistor. Figure 6 It can be seen that GeS 0.2 Se 0.8 The anisotropy of nanosheets enables phototransistors to have polarized light response capabilities, exhibiting different photocurrent response phenomena at different polarization angles. Figure 7 For h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G =60 V、V DS =0V, P=119.57 mW / cm 2 Current-time (IT) curves under given conditions. (From...) Figure 7 It can be seen that in the periodic laser switch test, the phototransistor outputs a stable negative photocurrent, with fast response speed and no obvious decay during cycling, demonstrating excellent photoelectric reversibility and working stability, and verifying the high sensitivity and high stability of the negative photoelectric response capability of the device under positive gate voltage. Figure 8 For h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G =-60 V、V DS =0V, P=119.57 mW / cm 2 Current-time (IT) curves under given conditions. (From...) Figure 8 It can be seen that under illumination, the phototransistor outputs a forward photocurrent, which is completely opposite in polarity to the positive gate voltage photocurrent, thus realizing the gate voltage reversible switching of the photocurrent polarity; the curve response is rapid and the cycle is stable, which fully confirms the feasibility, repeatability and low power consumption characteristics of the bidirectional photoresponse of the phototransistor. Figure 9 For h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V G =Polar coordinates of photocurrent at a gate voltage of 60 V. Figure 9 It can be seen that the photocurrent exhibits a bilobal distribution, reaching its maximum value in the armchair crystal orientation and its minimum value in the zigzag crystal orientation, with a polarization ratio as high as 17.4. This precisely quantifies the ultra-high polarization resolution capability of the phototransistor under the positive gate voltage, demonstrating the excellent performance of anisotropic photoelectric response. Figure 10 For h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in V GPolar coordinates of photocurrent at a gate voltage of -60 V. Figure 10 It can be seen that by maintaining the polarization response characteristics of the double-leaf type and achieving a polarization ratio of 11, reverse polarization detection under negative grid voltage can be realized. Figure 9 and Figure 10 Together, they confirmed that the phototransistor has the dual functions of gate voltage adjustable bidirectional optical response and full gate voltage high-sensitivity polarization detection, providing experimental support for multidimensional optical information detection.
[0027] Example 2
[0028] The difference from Example 1 is that: the selected germanium sulfoselenide is GeS. 0.4 Se 0.6 The ratio of sulfur atoms to selenium atoms is 2:3. Figure 11 Example 2 is based on h-BN / GeS 0.4 Se 0.6 The optical responsivity and optical power density relationship curves of the / WS2 heterojunction bidirectional polarization phototransistor under different gate voltages are derived from... Figure 11 It is evident that the photoresponsivity of the phototransistor is significantly lower than that of Example 1. This is because a large number of photogenerated carriers are lost before being transported to the electrodes, reducing carrier collection efficiency and directly limiting photocurrent and responsivity. In contrast, GeS... 0.2 Se 0.8 When used as a preferred composition, germanium sulfoselenide exhibits a more suitable bandgap matching relationship and higher carrier collection efficiency, resulting in superior photoresponse performance. Therefore, by reducing the ratio of sulfur atoms to selenium atoms, a heterojunction-based phototransistor with even better performance can be obtained.
[0029] Example 3
[0030] The difference from Example 1 is that in step 4, after depositing a 50nm Au electrode using an electron beam evaporation coating system and removing the photoresist with acetone to obtain a phototransistor with electrodes, the argon annealing step is not performed, and the probe test station is used directly for testing. Figure 12 Example 4 is based on h-BN / GeS 0.2 Se 0.8 / WS2 heterojunction bidirectional polarization phototransistor in unannealed form compared with h-BN / GeS in Example 1 0.2 Se 0.8 A comparison of voltage-current relationships in a / WS2 heterojunction bidirectional polarization phototransistor under annealing. Figure 12 It can be seen that the photocurrent of the phototransistor in Example 4 is significantly lower than that in Example 1. This is because when the phototransistor is not annealed, the metal and semiconductor in the phototransistor are only in physical contact, and the gaps at the interface lead to high contact resistance. In contrast, h-BN / GeS 0.2 Se 0.8The / WS2 heterojunction requires annealing before testing to reduce electrode contact resistance and facilitate carrier tunneling. Therefore, argon annealing is necessary before testing to obtain a phototransistor with superior performance.
[0031] Comparative Example 1 The difference from Example 1 is that: the selected germanium sulfoselenide is GeSe, and the test is performed without the doping of sulfur atoms. Figure 13 The graphs showing the relationship between photoresponsivity and optical power density of the h-BN / GeSe / WS2 heterojunction-based phototransistor in Comparative Example 1 at different gate voltages are provided by... Figure 13 It can be seen that the photoresponsivity of the phototransistor is significantly lower than that of Example 1. This is because the valence band shift between GeSe and WS2 is larger, requiring higher energy for photogenerated carriers to cross the potential barrier. In comparison, the performance using GeSe is lower than that using GeS2. 0.2 Se 0.8 Performance, GeS 0.2 Se 0.8 When used as a preferred composition, germanium sulfide selenide exhibits a more suitable bandgap matching relationship and higher carrier collection efficiency, resulting in superior photoresponse performance. Therefore, low-sulfur-doped alloys yield heterojunction-based phototransistors with superior performance.
[0032] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfoselenide / tungsten disulfide heterojunction, characterized in that, The bidirectional polarization phototransistor structure includes a SiO2 / Si substrate and an h-BN / GeS substrate. x Se y / WS2 heterojunction and electrodes, wherein the heterojunction is composed of h-BN, GeS x Se y Nanosheets and WS2 nanosheets overlap to form GeS x Se y In the model, x = 0.2~0.4, y = 0.6~0.8, and h-BN is a hexagonal boron nitride insulating layer; respectively, in non-overlapping GeS... x Se y Au electrodes were deposited on nanosheets and WS2 nanosheets and then annealed at 150-200°C under a protective gas atmosphere.
2. The bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction according to claim 1, characterized in that, The thickness of the Au electrode is 30-70 nm; the protective gas is nitrogen or argon; and the annealing time is 30-60 min.
3. The bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction according to claim 1, characterized in that, The GeS x Se y The thickness of the nanosheets is 40~50 nm, the thickness of the WS2 nanosheets is 25~30 nm, and the thickness of the h-BN is 5~10 nm.
4. The bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction as described in claim 3, characterized in that, The GeS x Se y The nanosheets are grown on a substrate using a low-pressure rapid physical vapor deposition method and obtained by mechanical pressing; the WS2 nanosheets are obtained on a cleaned SiO2 / Si substrate by mechanical exfoliation.
5. The method for fabricating a bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfoselenide / tungsten disulfide heterojunction according to any one of claims 1-4, characterized in that, The specific steps include the following: S1. GeS2 grown on SiO2 / Si substrate using low-pressure rapid physical vapor deposition. x Se y Nanosheets were mechanically pressed and transferred to a SiO2 / Si substrate using PDMS, and then the bright yellow GeS2 nanosheets were selected using an optical microscope. x Se y Nanosheets; S2. WS2 nanosheets were obtained on a cleaned SiO2 / Si substrate by mechanical exfoliation. The sample surface was removed by immersion in anhydrous ethanol to remove adhesive residue. The yellow-green WS2 nanosheets were selected by optical microscopy. S3. h-BN was deposited as an insulating layer on a SiO2 / Si substrate using a dry transfer method; WS2 nanosheets were transferred to GeS2 substrate using a dry transfer method. x Se y h-BN / GeS was prepared by first annealing on nanosheets at 100–150 °C under a protective gas atmosphere. x Se y / WS2 vertical heterojunction; S4. Using ultraviolet lithography, WS2 nanosheets and GeS2 nanosheets were fabricated. x Se y The source and drain electrodes were developed by photolithography on the nanosheet, and Au electrodes were deposited by electron beam evaporation. After the photoresist was dissolved by immersion in acetone, the fabricated device was subjected to a second annealing at 150-200°C to obtain the h-BN / GeS2 nanosheet based device. x Se y / WS2 heterojunction bidirectional polarization phototransistor.
6. The method for fabricating a bidirectional polarization phototransistor based on a hexagonal boron nitride / molybdenum ditelluride heterojunction according to claim 5, characterized in that, The first annealing time in step S3 is 30-60 min, the protective gas in step S4 is nitrogen or argon, and the second annealing time is 30-60 min.
7. The application of the bidirectional polarization phototransistor based on a hexagonal boron nitride / germanium sulfide selenide / tungsten disulfide heterojunction as described in any one of claims 1-4 in the field of optoelectronic devices for encrypted-decrypted information transmission.