Method for realizing photoelectric detector with infinite polarization ratio based on anisotropic two-dimensional material

Abstract

The invention provides a method for realizing an infinite polarization ratio photoelectric detector based on an anisotropic two-dimensional material. The specific preparation method of the device comprises the following steps: preparing a Ti / Au electrode on a Si / SiO2 substrate by using a standard photoetching process, and transferring two-dimensional ReSe2 and graphene (Gr) obtained by mechanical stripping to the electrode through dry transfer to form the polarized photoelectric detector based on the Au / ReSe2 / Gr back-to-back Schottky junction. The light current generated by the Gr / ReSe2 Schottky junction on the top layer and the light current generated by the Au / ReSe2 Schottky junction on the bottom layer are opposite, and the polarization response directions of the Gr / ReSe2 Schottky junction and the Au / ReSe2 Schottky junction have a 90-degree phase difference. The photocurrent contribution of the two Schottky junctions is regulated and controlled through the bias voltage, and the photoelectric detector with the infinite polarization ratio can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polarized light detection, and in particular relates to a method for realizing an infinite polarization ratio photoelectric detector based on anisotropic two-dimensional materials. Background Art

[0002] Photodetectors are core components of optoelectronic devices and can be used to sense optical information. Light is an electromagnetic wave that carries information such as intensity, phase, polarization, and wavelength. Light's polarization state changes during propagation, and this change in polarization state can be used to obtain a variety of information. Therefore, the detection of polarized light has important application value in industrial monitoring, medical and biological imaging, optical remote sensing and environmental monitoring, target identification, and astronomical observation. Traditional photodetectors can only detect the intensity of incident light, which limits their widespread application. In order to make traditional photodetectors polarization-sensitive, additional polarization elements need to be introduced, which increases the size and complexity of the system and is not conducive to the development trend of device integration and miniaturization.

[0003] Two-dimensional materials possess excellent optoelectronic properties, such as strong light-matter interactions, and have significant application potential in the field of photoelectric detection. Two-dimensional materials with in-plane anisotropy, such as black phosphorus and transition metal chalcogenides, can detect polarized light by utilizing their dichroism. However, this inherent anisotropic dichroism makes it difficult to control the photoresponse to light polarized in different directions. Detectors often have only a limited polarization extinction ratio, which greatly limits their application in polarization photoelectric detection. Summary of the Invention

[0004] In light of this, the present invention aims to provide a method for realizing an infinite polarization ratio photodetector based on anisotropic two-dimensional materials. This polarization light detector is composed of back-to-back Au / ReSe2 / Gr Schottky junctions fabricated by a fully dry transfer method. The Gr / ReSe2 Schottky junction on the top layer and the Au / ReSe2 Schottky junction on the bottom layer generate opposite photocurrents; and due to differences in polarized light absorption, the polarization response directions of the two junctions exhibit a 90° phase difference. By regulating the photocurrent contributions of the two Schottky junctions via bias voltage, a photodetector with infinite polarization ratio can be realized.

[0005] Based on the above purpose, the technical solution provided by the present invention comprises the following steps:

[0006] S1: All SiO2 / Si substrates must be pretreated before use by ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water for 10 minutes in sequence;

[0007] S2: All cleaned SiO2 / Si substrates were purged with a nitrogen gun and baked at 150°C for 10 min;

[0008] S3: The anisotropic two-dimensional semiconductor ReSe2 and the top electrode Gr are transferred to Si / SiO2 substrate 1 and Si / SiO2 substrate 2 respectively by mechanical exfoliation;

[0009] S4: Prepare Ti / Au bottom electrode on Si / SiO2 substrate 3 using standard photolithography process;

[0010] S5: At 70°C, Gr and ReSe2 are sequentially bonded from Si / SiO2 substrate 2 and substrate 1 through PVC;

[0011] S6: at 130°C, Gr and ReSe2 are released together onto a Si / SiO2 substrate 3 with a Ti / Au bottom electrode;

[0012] S7: The device is annealed at 150°C for 30 min.

[0013] Preferably, the two-dimensional semiconductor with anisotropy is ReSe2.

[0014] Preferably, the two-dimensional semiconductor with anisotropy is obtained by mechanical exfoliation and has a thickness of 80-150 nm.

[0015] Preferably, the top electrode is made of a transparent two-dimensional semi-metal material Gr.

[0016] Preferably, the top electrode is obtained by mechanical stripping and has a thickness of 3-15 nm.

[0017] Preferably, the two-dimensional semiconductor with anisotropy and the bottom electrode and the top electrode form a back-to-back Schottky junction.

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

[0019] 1. The present invention provides a method for preparing an infinite polarization ratio photodetector with adjustable bias voltage, which breaks the limitation of the inherent anisotropic dichroism of the material on the polarization response direction and polarization ratio of the polarization photodetector.

[0020] 2. The present invention uses a fully dry transfer process to fabricate polarization detection optoelectronic devices. This process requires no additional polarization components and does not involve any chemical solution treatment. It offers the advantages of simplicity, low cost, high repeatability, and no pollution.

[0021] 3. The anisotropic two-dimensional materials used in the present invention are universal and are not limited to ReSe2 in the preferred embodiment. The present invention is also applicable to other anisotropic two-dimensional materials such as ReS2, PdPS, and PdPSe. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0023] Figure 1 is a schematic structural diagram of the polarization photodetector;

[0024] Figure 2 Schematic diagram of the energy band structure of the device under different bias voltages;

[0025] Figure 3 Figure 2 shows the polarization photocurrent curves of the device under different bias voltages. (a) The circular data points are at a bias voltage of 1V, the rectangular data points are at a bias voltage of -1V, and the optical power is 5μW. (b), (c), and (d) The bias voltages are 70mV, 80mV, and 100mV, respectively, and the optical power is 64μW. The wavelength of light in all tests is 638nm.

[0026] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0027] 1. Substrate; 2. Bottom electrode; 3. Anisotropic two-dimensional material; 4. Top electrode. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Example 1

[0030] like Figure 1 As shown, an embodiment of the present invention provides an infinite polarization ratio photodetector based on anisotropic two-dimensional materials, including a Si / SiO2 substrate, a Ti / Au bottom electrode, anisotropic two-dimensional material ReSe2 and a top electrode Gr.

[0031] Figure 2 Schematic diagram of the energy band structure of the device in Example 1. Figure 2As can be seen in (a), the polarized light detector has two back-to-back Schottky junctions, Au / ReSe2 and Gr / ReSe2, and the photocurrents generated by the Gr / ReSe2 Schottky junction on the top layer and the Au / ReSe2 Schottky junction on the bottom layer are in opposite directions. The size of the Schottky barrier can be changed by the bias voltage, thereby regulating the direction of the photocurrent. Figure 2 As shown in (b), when a 1V bias voltage is applied, the Au / ReSe2 Schottky junction is reverse biased, the potential barrier increases, and the photocurrent increases; while the Gr / ReSe2 Schottky junction is forward biased, the potential barrier decreases, and the photocurrent decreases. Figure 2 As shown in (c), when the bias voltage is -1V, the photocurrent of the Au / ReSe2 Schottky junction decreases; while the photocurrent of the Gr / ReSe2 Schottky junction increases.

[0032] Figure 3 The curves of the polarized photocurrent of the device under different bias voltages in Example 1 are shown in FIG. Figure 3 As can be seen in (a), when the bias voltage is 1V and -1V respectively, there is a 90° phase difference between the polarized photocurrents of the device, and the polarization ratio is 1.3. Under a bias of 1V, the main contribution to the photocurrent comes from the bottom layer Au / ReSe2, while under a bias of -1V, the main contribution to the photocurrent is transformed into the top layer Gr / ReSe2 junction. Therefore, the phase difference comes from the difference in photocurrent contribution. This is because there is a difference in the absorption of polarized light at the surface and bottom of the thick layer ReSe2 material. Since the photocurrent contribution of the top and bottom Schottky junctions can be adjusted by the bias voltage, the device can achieve an infinite polarization ratio. As shown Figure 3 As shown in (b–d), under bias voltages of 70 mV, 80 mV, and 100 mV, the polarization ratios of the device are positive infinity, positive-negative infinity, and positive infinity, respectively.

[0033] According to the above analysis, Example 1 of the present invention realizes light detection with infinite polarization ratio by regulating the photocurrent contribution of the Au / ReSe2 and Gr / ReSe2 back-to-back Schottky junctions through bias voltage.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements within the spirit and principles of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for realizing an infinite polarization ratio photodetector based on anisotropic two-dimensional materials, characterized in that: The detector structure is composed of: substrate (1), bottom electrode (2), anisotropic two-dimensional material (3), top electrode (4) from bottom to top; wherein, The substrate (1) is a heavily doped Si substrate having a SiO2 layer; The bottom electrode (2) is a Ti / Au electrode, the bottom Ti thickness is 5nm, and the top Au thickness is 30nm; The anisotropic two-dimensional material (3) is a two-dimensional semiconductor ReSe2 with anisotropy and a thickness of 80-150 nm; The top electrode (4) is graphene (Gr) with a thickness of 3-15 nm.

2. The infinite polarization ratio photodetector according to claim 1, characterized in that: Preferably, the two-dimensional semiconductor with anisotropy is ReSe2.

3. The infinite polarization ratio photodetector according to claim 1, wherein: The two-dimensional semiconductor with anisotropy is obtained by mechanical exfoliation and has a thickness of 80-150 nm.

4. The method for realizing an infinite polarization ratio photodetector based on anisotropic two-dimensional materials according to claim 1, characterized in that: Preferably, the top electrode is made of a transparent two-dimensional semi-metal material Gr.

5. The infinite polarization ratio photodetector according to claim 1, wherein: The top electrode is obtained by mechanical stripping and has a thickness of 3-15 nm.

6. The infinite polarization ratio photodetector according to claim 1, wherein: The two-dimensional semiconductor with anisotropy and the bottom electrode and the top electrode form a back-to-back Schottky junction.

7. A method for realizing an infinite polarization ratio photodetector based on anisotropic two-dimensional materials, characterized in that: Device preparation includes the following steps: S1: All SiO2 / Si substrates must be pretreated before use by ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water for 10 minutes in sequence; S2: All cleaned SiO2 / Si substrates were purged with a nitrogen gun and baked at 150°C for 10 min; S3: Transferring the anisotropic two-dimensional semiconductor and top electrode to Si / SiO2 substrate 1 and Si / SiO2 substrate 2, respectively, by mechanical exfoliation. S4: Prepare Ti / Au bottom electrode on Si / SiO2 substrate 3 using standard photolithography process; S5: At 70°C, Gr and ReSe2 are sequentially bonded from Si / SiO2 substrate 2 and substrate 1 through PVC; S6: at 130°C, Gr and ReSe2 are released together onto a Si / SiO2 substrate 3 with a Ti / Au bottom electrode; S7: The device is annealed at 150°C for 30 min.

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