Two-dimensional material photoelectric detector based on quantum tunneling mechanism

Abstract

The invention relates to a two-dimensional material photoelectric detector based on a quantum tunneling mechanism. The two-dimensional material photoelectric detector comprises a grid electrode, an insulating layer, a P-type layer, an N-type layer, a protective layer, a source electrode leading-out end and a drain electrode leading-out end. The P-type layer, the N-type layer and the protective layer are sequentially transferred on the grid electrode and the insulating layer from bottom to top by a mechanical stripping dry method, the P-type layer is made of a wide-band-gap two-dimensional material, and the N-type layer is made of a narrow-band-gap two-dimensional material; photons are incident from the top, an anode leading-out end on the P-type layer is connected with a positive electrode of a power supply, a drain leading-out end on the N-type layer is connected with a negative electrode of the power supply, and the photons are absorbed by a PN junction space charge region. According to the invention, the process is simple, the design is compact, dark current and subthreshold swing can be greatly reduced in a high-temperature working environment, and the rectification ratio and the switching ratio are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to a two-dimensional material photoelectric detector based on a quantum tunneling mechanism. Background Art

[0002] Two-dimensional semiconductors have attracted great attention due to their interesting structures and rich layer-dependent physical properties, which also show high potential in next-generation optoelectronic and electronic devices. In addition, two-dimensional layered materials do not contain dangling bonds, which gives rise to the possibility of fabricating van der Waals heterostructures through their combination. The resulting van der Waals heterostructures with band alignment realize various functions and can therefore be used in lasers, field-effect transistors, memories, solar cells, logic rectifiers, and photodetectors. So far, there are three possible types of band alignment for heterostructures based on two-dimensional semiconductor materials: type I-straddling, type II-staggered, and type III-broken gap. Compared with the other two band alignments, type III heterostructures have non-overlapping band gaps between the two semiconductors and are widely used to design various high-speed, low-power devices due to the charge transport through the heterostructure by interband quantum tunneling. Such quantum tunneling can also greatly improve the drain current.

[0003] Broken-gap van der Waals heterostructures based on various combinations of 2D materials have been realized through different modulation methods such as gate coupling, thickness modulation, and chemical doping. These heterostructure devices, such as heterojunction field effect transistors and Esaki diodes, have attracted much attention due to their tunneling mechanism as heterojunction field effect transistors. Designing devices with large rectification ratios and high switching ratios is conducive to the development of multi-valued logic and binary inverters. In addition, for van der Waals heterostructure diodes, the rectification behavior is not only controlled by the Fermi level difference, but also by the valence band or conduction band offset between the two stacked materials. However, van der Waals heterostructures usually have a relatively small conduction band offset, in which the reverse and forward currents will increase synchronously, which will limit the rectification behavior of the device. Therefore, the on-current rectification ratio of the diode and the switching ratio of the transistor cannot usually be obtained simultaneously in the same heterojunction diode. In addition, for photodetectors, the increased drain current means a large dark current, which will further lead to a low photocurrent switching ratio. Summary of the invention

[0004] The purpose of the present invention is to provide a two-dimensional material photodetector based on quantum tunneling mechanism, which solves the problem that the on-current rectification ratio of the diode and the switching ratio of the transistor in the prior art cannot usually be obtained simultaneously in the same heterodiode. For the photodetector, the increased drain current means a large dark current, which will further lead to the defect of a low photocurrent switching ratio.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A two-dimensional material photodetector based on quantum tunneling mechanism, comprising a gate, an insulating layer, a P-type layer, an N-type layer, a protective layer, an anode lead terminal, and a cathode lead terminal; the anode lead terminal and the cathode lead terminal are arranged on the gate and the insulating layer as bottom electrodes, and the P-type layer, the N-type layer, and the protective layer are arranged in sequence from bottom to top on the insulating layer;

[0007] The P-type layer is a wide bandgap two-dimensional material made of tungsten diselenide or molybdenum disulfide, and the N-type layer is a narrow bandgap two-dimensional material made of palladium diselenide or platinum diselenide.

[0008] The gate is a conductive layer made of highly doped P-type silicon with a boron doping concentration of 5×10 17 ~5×10 18 per cubic centimeter; alternatively, the gate is a conductive layer made of graphene; the thickness of the gate ranges from 10 nanometers to 200 nanometers.

[0009] The insulating layer is an insulating material made of silicon dioxide or aluminum oxide or hexagonal boron nitride, and the thickness of the insulating layer ranges from 10 nanometers to 200 nanometers.

[0010] The P-type layer, the N-type layer and the protective layer are sequentially transferred to the insulating layer from bottom to top by a mechanical stripping dry method.

[0011] The protective layer is made of anti-oxidation material hexagonal boron nitride or PMMA A5 photoresist, and the thickness of the protective layer ranges from 10 nanometers to 200 nanometers.

[0012] The thickness of the P-type layer ranges from 10 nanometers to 200 nanometers; the thickness of the N-type layer ranges from 10 nanometers to 200 nanometers.

[0013] An anode lead-in terminal and a cathode lead-in terminal are evaporated on the gate electrode and the insulating layer as a bottom electrode.

[0014] The anode lead-out terminal is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, chromium or titanium is a contact layer in contact with the insulating layer, and gold is a metal conductive layer;

[0015] The cathode lead-out terminal is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, wherein the chromium or titanium is a contact layer in contact with the insulating layer, and the gold is a metal conductive layer.

[0016] In the chromium-gold double-layer electrode, the thickness of chromium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers; in the titanium-gold double-layer electrode, the thickness of titanium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers.

[0017] The beneficial effects of the present invention are: 1. A broken-gap van der Waals heterostructure is proposed, which uses a wide-bandgap P-type two-dimensional material combined with a narrow-bandgap N-type two-dimensional material to form a large conduction band offset to suppress the forward current. In this case, the narrow-bandgap two-dimensional material with high carrier concentration and high mobility can be used as an effective carrier-selective contact for reverse tunneling electrons, and there is almost no heterogeneous interface barrier. Therefore, the rectification ratio of the heterojunction diode can be greatly improved. Under illumination, the forward photocurrent can be significantly improved by light-controlled tunneling transport. In addition, its photogenerated tunneling electrons can quickly recombine with the majority of hole carriers in the opposite direction in the wide bandgap two-dimensional material aggregation area, reducing the interface capture effect and significantly improving the response speed; 2. By using the gate to control the Fermi level of the underlying wide bandgap two-dimensional material, and at the same time using the bias voltage to control the Fermi level of the wide bandgap and narrow bandgap two-dimensional materials at both ends of the source and drain, the band matching of the wide bandgap and narrow bandgap two-dimensional materials at both ends of the source and drain can be jointly controlled, and it is possible to switch from type II heterojunction to type III heterojunction, forming an interband quantum tunneling channel, switching from ultra-low dark current to ultra-high dark current, forming an ultra-large rectification ratio and a low subthreshold swing. Under illumination, photons will trigger the photoinduced tunneling mechanism of the heterojunction, generate a large photocurrent, and form an excellent optical switching ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention;

[0019] Figure 2 is the relationship between the dark current and the source-drain voltage of the embodiment of the present invention, and the ordinate is an exponential coordinate;

[0020] Figure 3 is the relationship between the dark current and the gate voltage in the implementation example of the present invention, and the ordinate is an exponential coordinate;

[0021] Figure 4 This is the relationship between the photocurrent and the source-drain voltage in the implementation example of the present invention, and the ordinate is an exponential coordinate.

[0022] In the figure: 1-gate; 2-insulating layer; 3-P-type layer; 4-N-type layer; 5-protective layer; 6-anode lead terminal; 7-cathode lead terminal. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings, which are only used for exemplary description and cannot be understood as limiting the present invention.

[0024] In order to more concisely describe the present embodiment, some parts known to those skilled in the art but not related to the main content of the present invention are omitted in the drawings or descriptions. In addition, for the convenience of description, some parts in the drawings are omitted, enlarged or reduced, but they do not represent the size or entire structure of the actual product.

[0025] The present invention discloses a two-dimensional material photoelectric detector based on quantum tunneling mechanism, such as Figure 1 As shown, it includes a gate 1, an insulating layer 2, a P-type layer 3, an N-type layer 4, a protective layer 5, an anode lead terminal 6, and a cathode lead terminal 7.

[0026] The gate 1 is a conductive layer made of highly doped P-type silicon with a boron doping concentration of 5×10 17 ~5×10 18 per cubic centimeter; alternatively, the gate 1 is a conductive layer made of graphene; the thickness of the gate 1 ranges from 10 nanometers to 200 nanometers.

[0027] The insulating layer 2 is an insulating material made of silicon dioxide, aluminum oxide or hexagonal boron nitride, and the thickness of the insulating layer 2 is in the range of 10 nanometers to 200 nanometers.

[0028] Acetone, isopropyl alcohol and deionized water are used to gradually clean the silicon wafer, the gate 1 and the insulating layer 2; PMMA A5 photoresist is spin-coated using a coating machine and then dried; electron beam lithography is used to photolithography the bottom electrode pattern, including the anode lead 6 and the cathode lead 7, and then developed.

[0029] The bottom electrode, including the anode terminal 6 and the cathode terminal 7, is completed using electron beam evaporation of the metal followed by lift-off.

[0030] The anode lead-out terminal 6 is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, chromium or titanium is a contact layer in contact with the insulating layer 2, and gold is a metal conductive layer;

[0031] The cathode lead-out terminal 7 is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, chromium or titanium is a contact layer in contact with the insulating layer 2, and gold is a metal conductive layer.

[0032] In the chromium-gold double-layer electrode, the thickness of chromium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers; in the titanium-gold double-layer electrode, the thickness of titanium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers.

[0033] After the anode lead-out terminal 6 and the cathode lead-out terminal 7 are fabricated, a P-type layer 3, an N-type layer 4, and a protective layer 5 are sequentially disposed on the insulating layer 2 in order from bottom to top.

[0034] The P-type layer 3 is a wide bandgap two-dimensional material made of tungsten diselenide or molybdenum disulfide, with a thickness ranging from 10 nanometers to 200 nanometers; the N-type layer 4 is a narrow bandgap two-dimensional material made of palladium diselenide or platinum diselenide, with a thickness ranging from 10 nanometers to 200 nanometers.

[0035] The protective layer 5 is made of an anti-oxidation material, hexagonal boron nitride or PMMA A5 photoresist, and the thickness of the protective layer 5 is in the range of 10 nanometers to 200 nanometers.

[0036] The P-type layer 3 , the N-type layer 4 and the protective layer 5 are sequentially transferred onto the insulating layer 2 from bottom to top by a mechanical stripping dry method.

[0037] Preferably, a transfer platform is used to transfer the P-type layer 3 of tungsten diselenide, with a thickness ranging from 10 nanometers to 200 nanometers; then the transfer platform is used to transfer the N-type layer 4 of platinum diselenide, with a thickness ranging from 10 nanometers to 200 nanometers; finally, the transfer platform is used to transfer the protective layer 5 of hexagonal boron nitride, with a thickness ranging from 10 nanometers to 200 nanometers.

[0038] Finally, the photoelectric detector of the present invention is manufactured.

[0039] like Figure 2 The figure shows the relationship between the dark current and the source-drain voltage of the photodetector of the present invention at a temperature of 300 Kelvin. The dark current is as low as 10 -11 Ampere, rectification ratio up to 10 4 .

[0040] like Figure 3 FIG. 1 shows the relationship between the dark current and the gate voltage of the photodetector of the present invention at a temperature of 300 Kelvin. The subthreshold swing is as low as 180 mV per order of magnitude.

[0041] like Figure 4 FIG. 1 is a graph showing the relationship between the photocurrent and the source-drain voltage of the photodetector of the present invention at a temperature of 300 Kelvin. The optical switching ratio exceeds 500 under 2.4 mW 520 nm laser irradiation.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the content of the patent application scope of the present invention should be within the technical scope of the present invention.

Claims

1. A two-dimensional material photodetector based on quantum tunneling mechanism, comprising a gate (1), an insulating layer (2), a P-type layer (3), an N-type layer (4), a protective layer (5), an anode lead terminal (6), and a cathode lead terminal (7); Features: An anode lead-out terminal (6) and a cathode lead-out terminal (7) are arranged on the gate electrode (1) and the insulating layer (2) as bottom electrodes, and a P-type layer (3), an N-type layer (4), and a protective layer (5) are arranged in order from bottom to top on the insulating layer (2); The P-type layer (3) is a wide bandgap two-dimensional material made of tungsten diselenide or molybdenum disulfide, and the N-type layer (4) is a narrow bandgap two-dimensional material made of palladium diselenide or platinum diselenide.

2. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 1, characterized in that: The gate (1) is a conductive layer made of highly doped P-type silicon with a boron doping concentration of 5×10 17 ~5×10 18 per cubic centimeter; Alternatively, the gate (1) is a conductive layer made of graphene; the thickness of the gate (1) ranges from 10 nanometers to 200 nanometers.

3. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 1, characterized in that: The insulating layer (2) is an insulating material made of silicon dioxide, aluminum oxide or hexagonal boron nitride, and the thickness of the insulating layer (2) ranges from 10 nanometers to 200 nanometers.

4. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 1, characterized in that: The P-type layer (3), the N-type layer (4) and the protective layer (5) are sequentially transferred onto the insulating layer (2) from bottom to top by a mechanical stripping dry method.

5. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 4, characterized in that: The protective layer (5) is made of an anti-oxidation material, hexagonal boron nitride or PMMA A5 photoresist, and the thickness of the protective layer (5) ranges from 10 nanometers to 200 nanometers.

6. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 4, characterized in that: The thickness of the P-type layer (3) ranges from 10 nanometers to 200 nanometers; the thickness of the N-type layer (4) ranges from 10 nanometers to 200 nanometers.

7. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 1, characterized in that: An anode lead-out terminal (6) and a cathode lead-out terminal (7) are evaporated on the grid (1) and the insulating layer (2) to serve as a bottom electrode.

8. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 7, characterized in that: The anode lead-out terminal (6) is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, wherein the chromium or titanium is a contact layer in contact with the insulating layer (2), and the gold is a metal conductive layer; The cathode lead-out terminal (7) is a chromium-gold double-layer electrode, or a titanium-gold double-layer electrode, wherein the chromium or titanium is a contact layer in contact with the insulating layer (2), and the gold is a metal conductive layer.

9. The two-dimensional material photodetector based on quantum tunneling mechanism according to claim 8, characterized in that: In the chromium-gold double-layer electrode, the thickness of chromium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers; in the titanium-gold double-layer electrode, the thickness of titanium is 5 nanometers to 100 nanometers, and the thickness of gold is 5 nanometers to 100 nanometers.

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