Molybdenum disulfide / diindium triselenide heterojunction phototransistor

Abstract

The invention belongs to the technical field of electronic components, and relates to a photoelectric transistor, in particular to a polarization sensitive photoelectric transistor with a MoS2 / In2Se3 heterojunction as a conducting layer. The MoS2 / In2Se3 heterojunction phototransistor comprises a Si / SiO2 substrate, a semiconductor MoS2 nanosheet, a semiconductor In2Se3 nanosheet, a source electrode and a drain electrode, the MoS2 nanosheet and the In2Se3 nanosheet form a vertical heterojunction located on the substrate, and the source electrode and the drain electrode are located at the two ends of the MoS2 / In2Se3 heterojunction. According to the invention, the MoS2 / In2Se3 heterojunction structure with intrinsic anisotropy is adopted to carry out polarized photoelectric detection, complicated optical components such as an additional optical polarizer and an optical filter are not needed, and the problems that a traditional polarized photoelectric detector is complicated in structure and cannot be integrated are solved; the two-dimensional material heterojunction with excellent photoelectric property is used as the conductive layer, so that the power consumption of the phototransistor is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic components and relates to a phototransistor, in particular to a polarization-sensitive phototransistor with a molybdenum disulfide / indium triselenide heterojunction as a conductive layer. Background Art

[0002] Light is an electromagnetic wave whose vibration direction is perpendicular to the propagation direction. Its main characteristics are amplitude, wavelength, phase and polarization. Among them, the polarization state carries a lot of important and effective information, which is difficult to obtain through intensity and wavelength (such as stress, surface roughness, etc.). And the polarization state is difficult to detect by traditional means (i.e. wavelength-sensitive and intensity-sensitive photodetectors). Therefore, the research on polarization detection is of practical significance. Polarization detection can not only distinguish the radiation intensity of the target and the background, but also obtain the polarization information of the target. Therefore, it has a significant effect in enhancing the information of the object being tested, improving the contrast, and promoting display and imaging. Polarization-sensitive photodetectors have attracted widespread attention because they play a vital role in both military and civilian fields, such as encrypted communications, meteorological monitoring and remote sensing.

[0003] Traditional photoelectric polarization detectors often face the problems of large dark noise and low light response. Due to their isotropy, they cannot directly detect polarized light. They usually need to be combined with filters and polarizers to achieve polarized light detection, which leads to a complex device structure and directly limits the realization of device miniaturization, integration and low power consumption. The new two-dimensional semiconductors have excellent electronic / photoelectronic properties due to their limited thickness. For example, their low carrier concentration makes the device dark noise weak, and the device can perform photoelectric detection at room temperature without refrigeration. The inherent structural asymmetry of the material makes its optical absorption exhibit typical optical anisotropy. These properties lay the foundation for the research of new room-temperature polarization photoelectric detection. However, the relevant research is still in its early stages, and the design and development of materials and device structures are still unclear. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention provides a polarization-sensitive phototransistor based on a molybdenum disulfide / indium triselenide heterojunction. This MoS2 / In2Se3 heterojunction phototransistor, due to its intrinsic anisotropy, enables direct polarization detection. As a novel two-dimensional layered semiconductor, it exhibits low carrier concentration, high mobility, low dark current, and high intrinsic gain. Compared to existing polarization detectors, this design offers a simpler structure, lower fabrication cost and complexity, and lower power consumption.

[0005] The MoS2 / In2Se3 heterojunction phototransistor provided by the present invention, as shown in Figure 1, includes a Si / SiO2 substrate 1, a semiconductor In2Se3 nanosheet 2, a semiconductor MoS2 nanosheet 3, a source electrode 4 and a drain electrode 5, and is characterized in that: the conductive layer structure of the polarization detector is that one end of the semiconductor In2Se3 nanosheet 2 contacts the drain electrode 5, and the other end extends to the channel region in the middle of the electrode; one end of the semiconductor MoS2 nanosheet 3 contacts the source electrode 4, and the other end overlaps with the semiconductor In2Se3 nanosheet 3 in the middle of the channel to form a vertical heterojunction.

[0006] The technical means adopted by the present invention is to construct a heterojunction phototransistor of MoS2 and In2Se3, appropriately select the direction and magnitude of the gate voltage and source-drain voltage, and utilize the intrinsic anisotropy of the heterojunction to achieve high-performance direct polarization detection of the transistor.

[0007] The Si / SiO2 substrate used in the present invention is a Si sheet with a 300nm thick SiO2 layer, the electrode uses a 20nm thick metal Ti layer, the In2Se3 nanosheet thickness is 6-63nm, the MoS2 nanosheet thickness is 4-8nm, and the semiconductor nanosheet is as thin as possible to improve the photoelectric conversion efficiency of the device.

[0008] In summary, the advantages of the present invention are:

[0009] Compared with traditional polarization photodetectors, the present invention uses the MoS2 / In2Se3 heterojunction structure for polarized light detection for the first time, without the need for additional complex optical components such as optical polarizers and filters. It solves the problem of complex structure and non-integration of traditional polarization photodetectors, and realizes self-driven polarization detection with a polarization ratio of 1.4; it uses a two-dimensional material heterojunction with excellent photoelectric properties as a conductive layer, and has good photoelectric response performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1(a) is a schematic diagram of the structure of the MoS2 / In2Se3 heterojunction phototransistor provided by the present invention, wherein 1 is the Si / SiO2 substrate, 2 is the semiconductor In2Se3 nanosheet, 3 is the semiconductor MoS2 nanosheet, 4 is the source electrode, and 5 is the drain electrode.

[0011] Figure 1(b) is a schematic diagram of an optical microscope photograph of a MoS2 / In2Se3 heterojunction phototransistor.

[0012] Figure 2(a) shows the V of the MoS2 / In2Se3 heterojunction phototransistor provided by the present invention under light with a wavelength of 532nm. ds =1.0V, V g = -3.0V and light with a wavelength of 808nm, V ds=1.0V when the photocurrent changes with the polarization angle.

[0013] Figure 2(b) shows the V of the MoS2 / In2Se3 heterojunction phototransistor provided by the present invention under light with a wavelength of 532nm. ds =1.0V, V g = -3.0V and light with a wavelength of 808nm, V ds =1.0V polar coordinate diagram of photocurrent changing with polarization angle. DETAILED DESCRIPTION

[0014] The present invention will be further described below with reference to specific embodiments so that the technical solution of the invention can be easily understood and grasped. However, the present invention is not limited to the following embodiments.

[0015] Example 1

[0016] The device structure is as described above, in which the thickness of the semiconductor In2Se3 nanosheet is 25nm, and the thickness of the semiconductor MoS2 nanosheet is 6nm. Figure 1 is a schematic diagram of the structure of the MoS2 / In2Se3 heterojunction phototransistor and a schematic diagram of an optical microscope photograph. The gate of the transistor is regulated by the back Si. As can be seen from Figure 1, the light gray on the nanosheets are electrodes, and the heterojunction channel layer is between the electrodes. The photoelectric performance and polarization detection performance of the heterojunction (the overlapping part of MoS2 / In2Se3) are tested by two electrodes. The test results of its polarization detection performance are shown in Figure 2; (a) The figure shows V at 532nm. ds =1.0V, V g =-3.0V and 808nm, V ds =1.0V, the sinusoidal fitting curve of photocurrent changing with polarization angle; (b) is the curve of V ds =1.0V, V g =-3.0V and 808nm, V ds =1.0 V. As shown in Figure 2, under positive bias, both the device with and without gate voltage can achieve polarization photodetection, with polarization ratios reaching 1.2 and 1.4, respectively.

[0017] The above description is only the best embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, combinations, simplifications, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A molybdenum disulfide / indium triselenide heterojunction phototransistor, comprising a Si / SiO2 substrate (1), a semiconductor In2Se3 nanosheet (2), a semiconductor MoS2 nanosheet (3), a source electrode (4) and a drain electrode (5), characterized in that: The conductive layer structure of the polarization detector is as follows: one end of a semiconductor In2Se3 nanosheet (2) contacts a drain electrode (5), and the other end extends to a channel region in the middle of the electrode; one end of a semiconductor MoS2 nanosheet (3) contacts a source electrode (4), and the other end overlaps with the semiconductor In2Se3 nanosheet (3) in the middle of the channel, forming a vertical van der Waals heterojunction.

2. The molybdenum disulfide / indium triselenide heterojunction phototransistor according to claim 1, characterized in that: It also includes a Si / SiO2 substrate (1), wherein the source electrode (4) and the drain electrode (5) are located on the surface of the substrate.

3. The molybdenum disulfide / indium triselenide heterojunction phototransistor according to claim 1, characterized in that: The Si / SiO2 substrate (1) is a Si sheet with a 300nm thick SiO2 layer.

4. The molybdenum disulfide / indium triselenide heterojunction phototransistor according to claim 1, characterized in that: The source electrode (4) and the drain electrode (5) are made of a metal Ti layer, and the thickness of the Ti layer is 20 nm.

5. The molybdenum disulfide / indium triselenide heterojunction phototransistor according to claim 1, characterized in that: The thickness of the semiconductor In2Se3 nanosheet (2) is 6-63nm, and the thickness of the MoS2 nanosheet (3) is 4-8nm. At the channel, the MoS2 nanosheet (3) partially covers the upper layer of the In2Se3 nanosheet (2) in the vertical direction.

6. The molybdenum disulfide / indium triselenide heterojunction phototransistor according to claim 1, characterized in that: The Si substrate serves as a back gate.

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