Polarized photodetector based on two-dimensional germanium selenide / molybdenum disulfide and preparation method thereof

Abstract

The application discloses a kind of based on two-dimensional germanium selenide / molybdenum disulfide polarized photoelectric detector and preparation method thereof, belong to the technical field of germanium selenide crystal material.The application discloses a kind of based on two-dimensional germanium selenide / molybdenum disulfide polarized photoelectric detector, adopt two-dimensional germanium selenide as anisotropic two-dimensional semiconductor layer, adopt molybdenum disulfide as two-dimensional semiconductor layer, molybdenum disulfide is main conductive channel, germanium selenide is as top layer photosensitive material, the built-in electric field of the PN junction formed in vertical direction, the separation of photo-generated carrier is enhanced, so as to improve photoelectric detection performance.Using the method of gas phase transmission, germanium selenide crystal is synthesized using germanium powder, selenium powder and crystalline iodine powder as anisotropic two-dimensional semiconductor layer two-dimensional germanium selenide, with the advantages of simple operation steps, low production cost, can be used for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of germanium selenide crystal material preparation technology, specifically relating to a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide and its preparation method. Background Technology

[0002] Photodetectors are fundamental components of modern information processing systems, converting optical signals into electrical signals. They play a crucial role in the development of electronic technologies such as military security, optical communication, and space technology. Polarization is an important optical information of light waves, in addition to intensity, frequency, and phase. Polarization-sensitive photodetectors can extract polarization information from incident light, shielding stray light to improve the signal-to-noise ratio and increase the amount of information obtained. Currently, traditional silicon-based photodetectors and gallium arsenide indium photodetectors dominate the optical detection market. However, these traditional photodetectors require the addition of polarizers and half-wave plates to the detection system to resolve polarization signals. This structure is not only very complex and difficult to integrate, but also suffers from low responsivity. Two-dimensional materials, with atomic-layer thickness, not only possess excellent electrical, optical, mechanical, and thermal properties, but also exhibit high transparency and good flexibility, making them ideal for novel device applications. Although two-dimensional layered semiconductors have high transparency, they can interact with the intensity of incident light, enhancing photon absorption and facilitating the generation of electron-hole pairs. Two-dimensional layered materials possess quantum confinement effects, facilitating the movement of charge carriers within a two-dimensional plane and simplifying research models for exploring charge carrier transport at the nanoscale. More importantly, the absence of dangling bonds on the surface of two-dimensional materials allows for layer-to-layer interactions via van der Waals forces. Therefore, van der Waals heterostructures based on any two-dimensional material can be stacked without considering lattice mismatch issues. Consequently, the rich family of two-dimensional materials, with its tunable performance and the potential for creating various heterostructures, makes them promising candidates for future high-performance optoelectronic devices, including photodetectors ranging from infrared to ultraviolet wavelengths.

[0003] Photodetectors fabricated using a single two-dimensional material and relying primarily on the photoconductivity effect suffer from drawbacks such as high dark current or long response time. Photovoltaic photodetectors utilize a PN junction to create a built-in electric field under illumination; while these devices offer faster response times, they lack additional gain mechanisms, resulting in lower photoresponsivity and detectivity. Photo-gate control is a special case of photoconductivity, characterized by a change in conductivity under illumination. Photoexcitation generates two types of charge carriers: one type is trapped in a trap state, while the other transports through the channel. The trapped carrier can be considered a local gate. Heterojunction structures based on photo-gate control are modulated through charge exchange or charge accumulation at the heterojunction interface. The built-in electric field at the interface enables effective electron-hole pair separation, and the photogenerated carriers in the top photo-gate layer act as a local gate to control the conductive channel.

[0004] With the further development of polarization-sensitive photodetectors, using two-dimensional semiconductor materials with intrinsic polarization sensitivity as the photosensitive medium of the detector provides an important approach to realizing polarization-sensitive photodetectors. Polarization photodetectors based on van der Waals heterojunctions can combine anisotropic materials with other materials to achieve high-performance photodetectors with polarization-sensitive characteristics.

[0005] Germanium selenide belongs to Group IV metal chalcogenides and possesses a highly anisotropic layered orthorhombic crystal structure. Its low-symmetry crystal structure endows it with excellent anisotropic properties in both optics and electronics. Using germanium selenide as a top-gate material in heterojunction photodetectors based on photo-gate control effects allows for localized gate modulation and enables polarization photodetection by leveraging its anisotropic light absorption characteristics. Currently, germanium selenide-based polarization photodetectors primarily utilize PN junction photodiodes, which, due to a lack of photoconductivity gain, suffer from poor photoresponsivity. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide and its fabrication method, so as to solve the technical problem of low photoresponsivity of traditional photodiode structures based on two-dimensional germanium selenide / molybdenum disulfide heterojunction.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention discloses a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide, comprising: a substrate layer, a two-dimensional semiconductor layer, two metal electrode layers, and an anisotropic two-dimensional semiconductor layer; the metal electrode layers are respectively disposed at both ends of the upper surface of the substrate layer as source and drain electrodes; the two-dimensional semiconductor layer is located between the two metal electrode layers and disposed on the upper surface of the substrate layer; the anisotropic two-dimensional semiconductor layer is located in the middle of the upper surface of the two-dimensional semiconductor layer and does not contact the two metal electrode layers; the material of the anisotropic two-dimensional semiconductor layer is two-dimensional germanium selenide; the material of the two-dimensional semiconductor layer is molybdenum disulfide.

[0009] Furthermore, the substrate layer includes a bottom gate electrode and a dielectric layer; the dielectric layer is located on the upper surface of the bottom gate electrode, and the two-dimensional semiconductor layer is located on the upper surface of the dielectric layer.

[0010] Furthermore, the dielectric layer is made of silicon dioxide, the gate electrode is made of silicon, and the substrate layer is 500–550 μm thick.

[0011] Furthermore, the material of the metal electrode layer is gold.

[0012] This invention also discloses a method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide, comprising the following steps:

[0013] S1: Two-dimensional germanium selenide was prepared as an anisotropic two-dimensional semiconductor layer using a chemical vapor transport method.

[0014] Germanium powder, selenium powder and crystalline iodine powder are mixed and placed into a quartz ampoule. The ampoule is then sealed by vacuuming. The sealed ampoule is placed in the reaction zone of a heating device for heating. Two-dimensional germanium selenide is obtained in the growth zone of the heating device.

[0015] S2: Molybdenum disulfide, which serves as a two-dimensional semiconductor layer, is transferred to the upper surface of the substrate layer using a dry transfer method.

[0016] The two metal electrodes were then transferred to both ends of the upper surface of the two-dimensional semiconductor layer;

[0017] S3: The two-dimensional germanium selenide obtained in S1 is used as an anisotropic two-dimensional semiconductor layer. The upper surface of the two-dimensional semiconductor layer is transferred by the alignment transfer method without contacting the two metal electrode layers, thus obtaining the pre-treated part.

[0018] S4: After heat treatment of the pre-processed part, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained.

[0019] Further, in S1, the mass ratio of germanium powder, selenium powder, and crystalline iodine powder is (1-1.1):(1-1.2):(4-6); the ampoule is sealed by vacuum evacuation, and the gas pressure inside the vacuum-sealed ampoule is lower than 1×10⁻⁶. - 3 Pa; When sealing the ampoule by evacuation, the crystalline iodine powder also needs to be fixed with liquid nitrogen.

[0020] Furthermore, in S1, the heating equipment is a dual-temperature zone tube furnace; the sealed ampoule is placed in the reaction zone of the dual-temperature zone tube furnace, and the reaction zone and growth zone of the dual-temperature zone tube furnace are heated to 600℃ and 530℃ respectively within 2 hours. After being kept at a constant temperature for 7-8 days, the temperature is naturally cooled down, and two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace.

[0021] Furthermore, the specific steps of the dry transfer technology are as follows:

[0022] Polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned with the upper surface of the substrate and then bonded together. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer to the upper surface of the substrate.

[0023] Furthermore, in S4, the heat treatment method is vacuum annealing.

[0024] Furthermore, the vacuum annealing temperature is 200℃~250℃, and the vacuum annealing time is 1.5h~2h.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention discloses a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide. Two-dimensional germanium selenide is used as the anisotropic two-dimensional semiconductor layer, and molybdenum disulfide is used as the two-dimensional semiconductor layer. Molybdenum disulfide forms the main conductive channel, and germanium selenide is used as the top photosensitive material. The built-in electric field of the PN junction in the vertical direction enhances the separation of photogenerated carriers, thereby improving photodetection performance. The application of this device in the field of photodetection solves the problems of low mobility, long response time, and low responsivity and detectivity of existing two-dimensional semiconductor photodetectors, further realizing polarization photodetection.

[0027] This invention also provides a method for preparing the above-mentioned polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide. The method uses chemical vapor deposition to synthesize high-purity germanium powder, selenium powder and crystalline iodine powder into high-quality layered germanium selenide crystals. The closed, stable and controllable synthesis environment of this method ensures the crystal quality of germanium selenide. Compared with commonly used chemical vapor deposition and wet chemical synthesis methods, chemical vapor deposition has advantages such as good controllability, high growth quality, simple operation, low cost and high reproducibility due to the unique synthesis environment. Attached Figure Description

[0028] Figure 1 This is a schematic cross-sectional view of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention.

[0029] Wherein: 1-substrate layer; 2-two-dimensional semiconductor layer; 3-metal electrode layer; 4-anisotropic two-dimensional semiconductor layer;

[0030] Figure 2 This invention presents a SEM image and its band structure diagram of two-dimensional germanium selenide prepared using a chemical vapor transport method.

[0031] Wherein: a-SEM image; b-Band diagram;

[0032] Figure 3 This is a schematic diagram of the carrier mobility of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention.

[0033] Figure 4 The photocurrent-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention is shown in the figure.

[0034] Figure 5 This is a graph showing the responsivity-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention.

[0035] Figure 6 The external quantum efficiency versus optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention is shown in the figure.

[0036] Figure 7 This is a graph showing the detectivity-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0038] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0039] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0040] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0041] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0044] Example 1

[0045] A method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide includes the following steps:

[0046] Step 1: Mix 1 mg of germanium powder, 1.1 g of selenium powder, and 5 g of crystalline iodine powder and place them into a quartz ampoule. The germanium and selenium powders serve as reaction precursors, and the crystalline iodine powder acts as a transport agent. Evacuate the ampoule to prevent iodine powder volatilization. During sealing, liquid nitrogen is used to fix the crystalline iodine powder. Place the sealed ampoule into the reaction zone of a dual-temperature zone tube furnace. Heat the reaction zone and growth zone of the dual-temperature zone tube furnace to 600°C and 530°C respectively within 2 hours. After 7 days of constant temperature, allow it to cool naturally. Two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace. The obtained two-dimensional germanium selenide is used as an anisotropic two-dimensional semiconductor layer 4. The pressure inside the vacuum-sealed ampoule is below 10⁻³ Pa. Silicon dioxide serves as the dielectric layer, and the bottom silicon layer serves as the gate.

[0047] S2: Polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned and bonded to the upper surface of substrate 1. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer 2 to the upper surface of substrate 1. The two-dimensional semiconductor layer 2 is transferred to substrate 1 to serve as the carrier channel of the device. Then, two metal electrodes 3 are transferred to both ends of the upper surface of the two-dimensional semiconductor layer 2 to serve as the source and drain electrodes. The substrate 1 is made of silicon / silicon dioxide and has a thickness of 550 μm.

[0048] S3: Select the long strip-shaped, uniformly thick thin layer of two-dimensional germanium selenide obtained in S1 as an anisotropic two-dimensional semiconductor layer 4. Transfer the middle part of the upper surface of the two-dimensional semiconductor layer 2 by alignment and transfer method, without contacting the two metal electrode layers 3, to obtain a pre-processed part; wherein the two-dimensional semiconductor layer 2 is selected as a thin layer with a large area and a thickness of 5-20 nanometers; the material of the metal electrode layer 3 is gold.

[0049] S4: After vacuum annealing the pretreated part at 200℃ for 2 hours, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained.

[0050] Example 2

[0051] A method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide includes the following steps:

[0052] Step 1: Mix 1g germanium powder, 1.1g selenium powder, and 6g crystalline iodine powder and place them into a quartz ampoule. The germanium and selenium powders serve as reaction precursors, and the crystalline iodine powder acts as a transport agent. Evacuate the ampoule to prevent iodine powder volatilization; liquid nitrogen is used to fix the crystalline iodine powder during sealing. Place the sealed ampoule into the reaction zone of a dual-temperature zone tube furnace. Heat the reaction zone and growth zone of the dual-temperature zone tube furnace to 600℃ and 530℃ respectively within 2 hours. After 7 days of constant temperature, allow it to cool naturally. Two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace. The obtained two-dimensional germanium selenide is used as the anisotropic two-dimensional semiconductor layer 4. The gas pressure inside the vacuum-sealed ampoule is below 10 kJ / m³. -3 Pa;

[0053] S2: The polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned and bonded to the upper surface of the substrate 1. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer 2 to the upper surface of the substrate 1. The two-dimensional semiconductor layer 2 is transferred to the substrate 1 to serve as the carrier channel of the device. Then, two metal electrodes 3 are transferred to the two ends of the upper surface of the two-dimensional semiconductor layer 2 to serve as the source and drain. The substrate 1 is made of silicon / silicon dioxide with a thickness of 500 μm. The silicon dioxide is the dielectric layer, and the bottom silicon layer serves as the gate.

[0054] S3: Select the long strip-shaped, uniformly thick thin layer of two-dimensional germanium selenide obtained in S1 as an anisotropic two-dimensional semiconductor layer 4. Transfer the middle part of the upper surface of the two-dimensional semiconductor layer 2 by alignment and transfer method, without contacting the two metal electrode layers 3, to obtain a pre-processed part; wherein the two-dimensional semiconductor layer 2 is selected as a thin layer with a large area and a thickness of 5-20 nanometers; the material of the metal electrode layer 3 is gold.

[0055] S4: After vacuum annealing the pretreated part at 200℃ for 1.5h, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained.

[0056] Example 3

[0057] A method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide includes the following steps:

[0058] Step 1: Mix 1g of germanium powder, 1g of selenium powder, and 5g of crystalline iodine powder and place them into a quartz ampoule. The germanium and selenium powders serve as reaction precursors, and the crystalline iodine powder acts as a transport agent. Evacuate the ampoule to prevent iodine powder volatilization; liquid nitrogen is used to fix the crystalline iodine powder during sealing. Place the sealed ampoule into the reaction zone of a dual-temperature zone tube furnace. Heat the reaction zone and growth zone of the dual-temperature zone tube furnace to 600℃ and 530℃ respectively within 2 hours. After 8 days of constant temperature, allow it to cool naturally. Two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace. The obtained two-dimensional germanium selenide is used as the anisotropic two-dimensional semiconductor layer 4. The gas pressure inside the vacuum-sealed ampoule is below 10... -3 Pa;

[0059] S2: The polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned and bonded to the upper surface of the substrate 1. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer 2 to the upper surface of the substrate 1. The two-dimensional semiconductor layer 2 is transferred to the substrate 1 to serve as the carrier channel of the device. Then, two metal electrodes 3 are transferred to the two ends of the upper surface of the two-dimensional semiconductor layer 2 to serve as the source and drain. The substrate 1 is made of silicon / silicon dioxide with a thickness of 500 μm. The silicon dioxide is the dielectric layer, and the bottom silicon layer serves as the gate.

[0060] S3: Select the long strip-shaped, uniformly thick thin layer of two-dimensional germanium selenide obtained in S1 as an anisotropic two-dimensional semiconductor layer 4. Transfer the middle part of the upper surface of the two-dimensional semiconductor layer 2 by alignment and transfer method, without contacting the two metal electrode layers 3, to obtain a pre-processed part; wherein the two-dimensional semiconductor layer 2 is selected as a thin layer with a large area and a thickness of 5-20 nanometers; the material of the metal electrode layer 3 is gold.

[0061] S4: After vacuum annealing the pretreated part at 250℃ for 1.5h, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained.

[0062] Example 4

[0063] A method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide includes the following steps:

[0064] Step 1: Mix 1.1g germanium powder, 1.2g selenium powder, and 6g crystalline iodine powder and place them into a quartz ampoule. The germanium and selenium powders serve as reaction precursors, and the crystalline iodine powder acts as a transport agent. Evacuate the ampoule to prevent iodine powder volatilization; liquid nitrogen is used to fix the crystalline iodine powder during sealing. Place the sealed ampoule into the reaction zone of a dual-temperature zone tube furnace. Heat the reaction zone and growth zone of the dual-temperature zone tube furnace to 600℃ and 530℃ respectively within 2 hours. After 7 days of constant temperature, allow it to cool naturally. Two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace. The obtained two-dimensional germanium selenide is used as an anisotropic two-dimensional semiconductor layer 4. The gas pressure inside the vacuum-sealed ampoule is below 10... -3 Pa;

[0065] S2: The polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned and bonded to the upper surface of the substrate 1. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer 2 to the upper surface of the substrate 1. The two-dimensional semiconductor layer 2 is transferred to the substrate 1 to serve as the carrier channel of the device. Then, two metal electrodes 3 are transferred to the two ends of the upper surface of the two-dimensional semiconductor layer 2 to serve as the source and drain. The substrate 1 is made of silicon / silicon dioxide with a thickness of 500 μm. The silicon dioxide is the dielectric layer, and the bottom silicon layer serves as the gate.

[0066] S3: Select the long strip-shaped, uniformly thick thin layer of two-dimensional germanium selenide obtained in S1 as an anisotropic two-dimensional semiconductor layer 4. Transfer the middle part of the upper surface of the two-dimensional semiconductor layer 2 by alignment and transfer method, without contacting the two metal electrode layers 3, to obtain a pre-processed part; wherein the two-dimensional semiconductor layer 2 is selected as a thin layer with a large area and a thickness of 5-20 nanometers; the material of the metal electrode layer 3 is gold.

[0067] S4: After vacuum annealing the pretreated part at 250℃ for 1.5h, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained.

[0068] Figure 1 The diagram shows a cross-sectional view of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen that it includes: a substrate layer 1, a two-dimensional semiconductor layer 2, two metal electrode layers 3, and an anisotropic two-dimensional semiconductor layer 4. The metal electrode layers 3 are respectively disposed at both ends of the upper surface of the substrate layer 1 as the source and drain. The two-dimensional semiconductor layer 2 is located between the two metal electrode layers (3) and is disposed on the upper surface of the substrate layer 1. The anisotropic two-dimensional semiconductor layer 4 is located in the middle of the upper surface of the two-dimensional semiconductor layer 2 and does not contact the two metal electrode layers 3.

[0069] Figure 2The image shows the SEM image and band structure diagram of two-dimensional germanium selenide prepared by the chemical vapor transport method of this invention. It can be seen from the image that the prepared germanium selenide crystal is indeed a layered material with a large area and a very smooth surface. From the calculated band structure, it can be seen that monolayer germanium selenide is an indirect bandgap semiconductor.

[0070] Figure 3 The figure shows a schematic diagram of the carrier mobility of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen from the figure that the carrier mobility of this structure can reach up to 58 cm⁻¹. 2 V -1 s -1 The carrier mobility is higher than that of devices using molybdenum disulfide as the channel, which is directly due to the fact that the germanium selenide layer on the channel promotes carrier transport.

[0071] Figure 4 The figure shows the photocurrent-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen from the figure that the photocurrent increases with increasing light intensity, and the photocurrent increases within the incident light power density range of 0.02–20 mW / cm². 2 The internal temperature has not reached saturation, and the maximum photocurrent can reach 3.6μA.

[0072] Figure 5 The figure shows the responsivity-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen from the figure that the responsivity decreases with increasing light intensity, which is a typical result of the photo-gravitational effect. The maximum responsivity can reach 6 × 10⁻⁶. 3 The A / W ratio is at a fairly high level among photodetectors currently reported by scientific research.

[0073] Figure 6 The figure shows the external quantum efficiency versus optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen from the figure that the external quantum efficiency exhibits a similar trend to the responsivity, decreasing with increasing light intensity, with a maximum external quantum efficiency reaching 1.4 × 10⁻⁶. 6 %, indicating extremely high photoconductivity gain.

[0074] Figure 7 The figure shows the detectivity-optical power density relationship of the polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide of the present invention. It can be seen from the figure that the detectivity exhibits a similar trend to the responsivity, decreasing with increasing light intensity, reaching a maximum of 7 × 10⁻⁶. 16 Jones is currently at a leading level internationally.

[0075] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide, characterized in that, Includes the following steps: S1: Two-dimensional germanium selenide was prepared as an anisotropic two-dimensional semiconductor layer using a chemical vapor transport method (4): Germanium powder, selenium powder and crystalline iodine powder are mixed and placed into a quartz ampoule. The ampoule is then sealed by vacuuming. The sealed ampoule is placed in the reaction zone of a heating device for heating. Two-dimensional germanium selenide is obtained in the growth zone of the heating device. S2: Molybdenum disulfide, which serves as a two-dimensional semiconductor layer (2), is transferred to the upper surface of the substrate layer (1) using a dry transfer method; The two metal electrodes (3) were then transferred to both ends of the upper surface of the two-dimensional semiconductor layer (2); S3: The two-dimensional germanium selenide obtained in S1 is used as an anisotropic two-dimensional semiconductor layer (4). The middle part of the upper surface of the two-dimensional semiconductor layer (2) is transferred by the alignment transfer method without contacting the two metal electrode layers (3) to obtain the pre-treated part. S4: After heat treatment of the pre-processed part, a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide is obtained. In S1, the mass ratio of germanium powder, selenium powder, and crystalline iodine powder is (1~1.1):(1~1.2):(4~6); the ampoule is vacuum-sealed, and the gas pressure inside the vacuum-sealed ampoule is lower than 1×10⁻⁶. -3 Pa; When sealing the ampoule tube by vacuuming, the crystalline iodine powder also needs to be fixed with liquid nitrogen; the heating equipment is a dual-temperature zone tube furnace; the sealed ampoule tube is placed in the reaction zone of the dual-temperature zone tube furnace, and the reaction zone and growth zone of the dual-temperature zone tube furnace are heated to 600℃ and 530℃ respectively within 2 hours. After being kept at a constant temperature for 7-8 days, it is naturally cooled down, and two-dimensional germanium selenide is obtained in the growth zone of the dual-temperature zone tube furnace; The polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide includes: a substrate layer (1), a two-dimensional semiconductor layer (2), two metal electrode layers (3), and an anisotropic two-dimensional semiconductor layer (4); the metal electrode layers (3) are respectively disposed at both ends of the upper surface of the substrate layer (1) as source and drain; the two-dimensional semiconductor layer (2) is located between the two metal electrode layers (3) and disposed on the upper surface of the substrate layer (1); the anisotropic two-dimensional semiconductor layer (4) is located in the middle of the upper surface of the two-dimensional semiconductor layer (2) and does not contact the two metal electrode layers (3); the material of the anisotropic two-dimensional semiconductor layer (4) is two-dimensional germanium selenide; the material of the two-dimensional semiconductor layer (2) is molybdenum disulfide.

2. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 1, characterized in that, The substrate layer (1) includes a bottom gate electrode and a dielectric layer; the dielectric layer is located on the upper surface of the bottom gate electrode, and the two-dimensional semiconductor layer (2) is located on the upper surface of the dielectric layer.

3. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 2, characterized in that, The dielectric layer is made of silicon dioxide, and the gate electrode is made of silicon; the substrate layer (1) is 500~550μm thick.

4. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 1, characterized in that, The material of the metal electrode layer (3) is gold.

5. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 1, characterized in that, The specific steps of the dry transfer technology are as follows: The polydimethylsiloxane with molybdenum disulfide attached is fixed on a glass slide. Using a two-dimensional material transfer platform and the alignment function of a microscope, the molybdenum disulfide is aligned with the upper surface of the substrate layer (1) and then bonded. After heating, the glass slide is lifted to complete the attachment of the two-dimensional semiconductor layer (2) to the upper surface of the substrate layer (1).

6. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 1, characterized in that, In S4, the heat treatment method is vacuum annealing.

7. The method for fabricating a polarization photodetector based on two-dimensional germanium selenide / molybdenum disulfide according to claim 6, characterized in that, The vacuum annealing temperature is 200℃~250℃, and the vacuum annealing time is 1.5h~2h.

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