Infrared detector with Van der Waals complementary barrier structure, preparation method and application

Abstract

The invention discloses an infrared detector with a Van der Waals complementary barrier structure, a preparation method and an application. The structure of the detector is as follows: a P-type Si substrate is used as a substrate of the detector; growing a SiO2 dielectric layer on the P-type Si substrate; the black phosphorus layer covers the SiO2 dielectric layer and is used as a conducting channel; one end of the molybdenum disulfide layer covers one end of the black phosphorus layer, and the other end of the molybdenum disulfide layer is arranged on the SiO2 dielectric layer; the drain electrode is directly prepared on the other end of the black phosphorus layer and is in contact with the black phosphorus layer; the source electrode is prepared at the other end, not overlapped with the black phosphorus layer, of the molybdenum disulfide layer, and electric connection is achieved through overlapping of the molybdenum sulfide layer and the black phosphorus layer. According to the invention, high-sensitivity room temperature detection, ultra-fast response and sensing of multiple physical quantities such as light intensity, polarization and gas are realized, and the method has an application prospect in a miniaturized, low-power-consumption and multifunctional infrared detection system.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to an infrared detector with a van der Waals complementary barrier structure, a preparation method and an application thereof. Background Art

[0002] The complementary barrier structure is a special energy band engineering design used in semiconductor devices. It consists of an n-type contact layer, a hole barrier layer, an absorption layer, an electron barrier layer and a p-type contact layer. It is mainly used to optimize the carrier transport characteristics and suppress leakage current. It forms complementary energy band barriers by alternating material layers with different barrier heights, thereby achieving precise control of carrier transport.

[0003] To address the primary source of dark current in superlattice infrared detectors, complementary barrier infrared detectors (CBIRs) have been proposed. Conventional CBIRs are based on epitaxially grown bulk materials. While bandgap engineering effectively suppresses dark current, their heteroepitaxial growth leads to the presence of dangling bonds and dislocations at the barrier layer interface, increasing non-radiative carrier recombination, lattice mismatch, and interface defects, degrading device performance. This defect-assisted dark current mechanism forces device operation at low temperatures, hindering the development of high-performance room-temperature CBIRs. Two-dimensional semiconductor materials, due to their lack of dangling bonds, exhibit excellent carrier transport properties and high light absorption coefficients, and hold significant promise for infrared detection.

[0004] Black phosphorus has excellent properties such as bipolar transmission, high carrier mobility, polarization sensitivity, high infrared absorption, and compatibility with silicon-based processes. It shows great potential in optoelectronic applications in the near-infrared to mid-infrared band. The Schottky barrier formed at the metal-semiconductor interface has the advantages of high-speed response, simple preparation process, and compatibility with silicon electronic devices and sensors. It plays an important role in high-speed optical communications and photoelectric detection. However, the performance of Schottky photodetectors, especially blackbody sensitivity, is limited by two major challenges: first, the Fermi pinning effect of the Schottky barrier of two-dimensional materials makes it difficult to achieve a preset barrier height; second, narrow-bandgap semiconductors generate a large dark current due to thermal excitation at room temperature, resulting in a poor photocurrent signal-to-noise ratio. Therefore, existing two-dimensional infrared Schottky photodetectors have poor performance and lack blackbody sensitivity. Summary of the Invention

[0005] A first object of the present invention is to provide an infrared detector with a van der Waals complementary barrier structure to address the problems in the prior art.

[0006] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] An infrared detector with a van der Waals complementary barrier structure, wherein the structure of the detector is:

[0008] The P-type Si substrate serves as the base of the detector;

[0009] A SiO2 dielectric layer is grown on a P-type Si substrate;

[0010] The black phosphorus layer covers the SiO2 dielectric layer and acts as a conductive channel;

[0011] One end of the molybdenum disulfide layer covers one end of the black phosphorus layer, and the other end is located on the SiO2 dielectric layer;

[0012] The drain electrode is directly prepared on the other end of the black phosphorus layer and is in contact with the black phosphorus layer;

[0013] The source electrode is prepared at the other end of the molybdenum disulfide layer that does not overlap with the black phosphorus layer, and electrical connection is achieved through the overlapping of the molybdenum disulfide layer and the black phosphorus layer.

[0014] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0015] As a preferred technical solution of the present invention: the P-type Si substrate is a P-type heavily doped Si substrate.

[0016] As a preferred technical solution of the present invention: the drain electrode is an Au electrode, and the thickness of Au on the black phosphorus layer is 50 nanometers;

[0017] The source electrode is a Cr and Au electrode, the thickness of Cr on the molybdenum disulfide layer is 10 nanometers, and the thickness of Au on the Cr is 90 nanometers.

[0018] As a preferred technical solution of the present invention: the thickness of the SiO2 dielectric layer is 285 nanometers;

[0019] The thickness of the black phosphorus layer is 40 to 50 nanometers;

[0020] The thickness of the molybdenum disulfide layer is 15 to 30 nanometers.

[0021] A second object of the present invention is to provide a method for preparing an infrared detector with a van der Waals complementary barrier structure in response to the problems in the prior art.

[0022] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0023] The van der Waals complementary barrier structure infrared detector comprises the following steps:

[0024] 1) Mechanically peeling off the black phosphorus layer from the black phosphorus bulk material and transferring it onto the SiO2 dielectric layer;

[0025] 2) The MoS2 layer is peeled off from the MoS2 bulk material by mechanical exfoliation and transferred to one end of the black phosphorus layer by micro-area fixed-point transfer;

[0026] 3) Depositing chromium and gold source electrodes on one end of the pre-transferred MoS2 layer using processes such as electron beam lithography, thermal evaporation, and lift-off;

[0027] 4) A customized transfer electrode gold is transferred to the surface of the black phosphorus layer through the micro-area fixed-point transfer method to form a drain.

[0028] The third object of the present invention is to provide an application of an infrared detector with a van der Waals complementary barrier structure to address the problems in the prior art.

[0029] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0030] The infrared detector with the van der Waals complementary barrier structure is used to realize infrared imaging, gas detection and polarization resolution in the same device.

[0031] Compared with the prior art, the infrared detector, preparation method and application of the van der Waals complementary barrier structure of the present invention have the following beneficial effects:

[0032] The present invention combines narrow-bandgap black phosphorus (BP) with wide-bandgap molybdenum disulfide (MoS2) to form a van der Waals heterostructure, avoiding lattice mismatch. The Schottky barrier formed by gold and black phosphorus blocks electron diffusion, while the wide-bandgap nature of MoS2 blocks hole migration, forming a complementary barrier. Through band engineering, carriers are blocked, significantly reducing dark current. The infrared photodetector constructed from molybdenum disulfide and black phosphorus exhibits a unique band structure, with gold and black phosphorus forming an electron barrier and molybdenum disulfide forming a hole barrier. This unique complementary barrier band structure effectively reduces surface leakage and diffusion current without suppressing photocurrent. The electron barrier formed by gold and black phosphorus, combined with the n-type doped barrier layer (hole barrier), introduces a space charge region, endowing the device with photovoltaic properties and self-powering capability. Using narrow-bandgap black phosphorus as the absorption layer, it achieves wide spectral response in the mid-wave infrared and polarization detection with a high extinction ratio. By utilizing the complementary barrier structure, the device achieves highly sensitive room-temperature blackbody detection and gas detection, and the device's response rate reaches 51 microseconds under a 1060-nanometer laser.

[0033] The present invention discloses an infrared detector with a van der Waals complementary barrier structure. Black phosphorus serves as a narrow-bandgap absorption layer, the Schottky barrier formed between gold and black phosphorus serves as an electron barrier, and the wide-bandgap material MoS2 serves as a hole barrier. The drain electrode is a customized transfer electrode made of gold, which effectively avoids the Fermi-level pinning effect. The complementary barrier structure composed of electron and hole barriers effectively suppresses the huge dark current generated by thermal excitation in the narrow-bandgap material black phosphorus. The van der Waals complementary barrier infrared detector proposed in the present invention has high blackbody sensitivity, with a peak detection rate (D*) of 8.37×109 cm Hz 1 / 2 W -1 , achieving a medium-wave infrared response of 3.6 microns, while having high polarization detection capability (anisotropy ratio of 13.9) and sensitive infrared gas detection capability (methane detection limit can reach 23.9 ppm).

[0034] The present invention solves the problems of dark current, speed and multi-functional integration of narrow-bandgap infrared detectors at room temperature through material innovation of BP / MoS2 heterojunction, band design of complementary potential barriers and process optimization of Au electrodes, and realizes high-sensitivity room-temperature detection, ultrafast response, and perception of multiple physical quantities such as light intensity, polarization, and gas. It has application prospects in miniaturized, low-power, and multi-functional infrared detection systems.

[0035] The infrared detector of the van der Waals complementary barrier structure, the preparation method and the application of the present invention realize applications in the fields of room temperature blackbody detection, polarization detection and gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the device structure of the infrared detector of the van der Waals complementary barrier structure of the present invention; In the figure: P-type Si substrate 1, dielectric layer 2, black phosphorus layer 3, molybdenum disulfide layer 4, drain 5, source 6; Figure 2 is the energy band diagram of the infrared detector under illumination; Figure 3 This is the detection rate curve of the infrared detector at different gate voltages; Figure 4 is the response time of the infrared detector under 1.06 μm laser; Figure 5 Polarization detection of infrared detectors under 1000K blackbody; Figure 6 Methane gas is used for demonstration of room temperature gas detection by infrared detectors. DETAILED DESCRIPTION

[0037] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, an infrared detector of a van der Waals complementary barrier structure of the present invention comprises a P-type Si substrate 1, a SiO2 dielectric layer 2, a black phosphorus layer 3, a molybdenum disulfide layer 4, a drain 5, a source 6,

[0039] The structure of the detector is as follows: a SiO2 dielectric layer 2 is provided on a P-type Si substrate 1, a black phosphorus layer 3 covers the SiO2 dielectric layer 2, one end of the black phosphorus layer 3 is covered with a molybdenum disulfide layer 4, the other end of the black phosphorus layer 3 is provided with a drain 5, one end of the molybdenum disulfide layer 4 covers the black phosphorus layer 3, and the other end of the molybdenum disulfide layer 4 is provided with a source 6.

[0040] The P-type Si substrate 1 is a P-type heavily doped Si substrate;

[0041] The thickness of the SiO2 dielectric layer 2 is 285 nanometers;

[0042] The thickness of the black phosphorus layer 3 is 40 to 50 nanometers;

[0043] The thickness of the molybdenum disulfide layer 4 is 15 to 30 nanometers;

[0044] The drain electrode 5 is an Au electrode, and the thickness of Au on the black phosphorus layer is 50 nanometers;

[0045] The source electrode 6 is a Cr and Au electrode, the thickness of Cr on the molybdenum disulfide layer is 10 nanometers, and the thickness of Au on the Cr is 90 nanometers.

[0046] The method for preparing the infrared detector with a van der Waals complementary barrier structure comprises the following steps:

[0047] 1) peeling off the black phosphorus layer 3 from the black phosphorus bulk material by mechanical stripping and transferring it onto the SiO2 dielectric layer 2;

[0048] 2) peeling the molybdenum disulfide layer 4 from the molybdenum disulfide bulk material by mechanical stripping and transferring it to one end of the black phosphorus layer 3 by micro-area fixed-point transfer;

[0049] 3) Depositing a chromium and gold source electrode 6 on one end of the pre-transferred molybdenum disulfide layer 4 using processes such as electron beam exposure, thermal evaporation, and lift-off.

[0050] 4) A customized transfer electrode gold is transferred to the surface of the black phosphorus layer 3 by a micro-area fixed-point transfer method to form a drain electrode 5.

[0051] The advantages of this invention lie in its vertical van der Waals complementary barrier structure, which effectively reduces dark current without suppressing photocurrent, thereby improving device performance and enabling room-temperature mid-wave infrared blackbody detection. Furthermore, the device boasts room-temperature operation, high sensitivity, a wide bandwidth, and fast response, promising applications in blackbody detection, polarization detection, and gas detection.

[0052] The invention introduces a complementary barrier structure into a two-dimensional material detector. The detector is based on the optimized design of the band structure and uses the barrier layer to block carriers, thereby reducing dark current, and can achieve high-sensitivity and high-speed room-temperature blackbody detection of the device.

[0053] Example

[0054] The van der Waals complementary barrier infrared detector of the present invention can effectively suppress dark current through a unique complementary barrier structure design, thereby improving the detection rate of the device and ultimately achieving room temperature blackbody detection and gas detection.

[0055] The specific steps are as follows: Substrate selection: Heavily doped p-type silicon is selected as the substrate, and the thickness of the SiO2 dielectric layer is about 285 nanometers.

[0056] 2D material transfer: The two-dimensional materials, molybdenum disulfide layer and black phosphorus layer, were peeled off in sequence by mechanical peeling. Then, in a nitrogen box, the black phosphorus layer and the molybdenum disulfide layer are transferred to the SiO2 dielectric layer in turn through the fixed-point transfer method, so that the black phosphorus layer is at the bottom, the molybdenum disulfide layer covers one end of the black phosphorus layer, and the other end of the molybdenum disulfide layer is partially covered on the SiO2 dielectric layer.

[0057] Source and drain preparation: Electron beam exposure is used to precisely position and expose the electrode pattern, and then PMMA developer is used for development. Metal electrodes are prepared using thermal evaporation technology, with 10 nanometers for chromium and 90 nanometers for gold. Finally, the metal film is peeled off by soaking in acetone solution for 10 minutes to obtain a metal source electrode on a separate molybdenum disulfide layer.

[0058] The drain electrode is a customized 50-nanometer gold film transferred onto the black phosphorus layer through a point-to-point transfer method.

[0059] The schematic diagram of the prepared van der Waals complementary barrier structure infrared detector is shown in Figure 1 Performance indicators are shown as follows. Figure 3 , Figure 4 , Figure 5 and Figure 6 shown.

[0060] Figure 2 This is the energy band diagram of an infrared detector under illumination. The Schottky barrier formed by gold and black phosphorus acts as an electron barrier, while molybdenum disulfide acts as a hole barrier. Together, these two barriers form a complementary barrier band structure, with black phosphorus serving as the absorption layer. When light strikes the device surface, electron-hole pairs are generated in the black phosphorus absorption layer. Under the influence of the built-in electric field, electrons are collected along the conduction band by the anode, while holes are directly collected by the cathode.

[0061] Figure 3 The device shows excellent room-temperature blackbody detection capability, with a detection cutoff wavelength of 3.6 microns and a peak detectivity of 8.37×10 9 cm Hz 1 / 2 W -1 .

[0062] Figure 4 This is the response time of the infrared detector to 1.06 μm laser light. The rising edge time is defined as the time required for the photocurrent to increase from 10% to 90%, and the falling edge time is defined as the time required for the photocurrent to decrease from 90% to 10%. Under 1.06 μm laser light, the device's rising edge time is 63 μs, and the falling edge time is 51 μs.

[0063] Figure 5 Polarization detection of an infrared detector under a 1000K blackbody light source. Under a non-polarized blackbody light source, a half-wave plate and a polarizer were placed in the optical path. By modulating the blackbody light source, the photocurrent at different polarization angles was recorded in a phase-locked manner. The device's extinction ratio under the blackbody light source was ultimately determined to be approximately 13.9. This demonstrates that the device can achieve high-performance polarization detection without external optical lenses.

[0064] Figure 6 It is a room temperature gas detection of infrared detectors. It uses a blackbody light source as the signal source, and adds a gas chamber and a filter in the optical path between the light source and the detector. The filter ensures the accuracy of gas absorption. Different concentrations of methane gas are introduced into the gas chamber. Figure 6 The inset shows a gradient plot of the signal value versus concentration. Based on this, a Beer-Lambert law fit was performed, ultimately yielding a detection limit of 23.9 ppm, demonstrating the device's excellent detection performance.

[0065] The present invention discloses an infrared detector, preparation method and application of a van der Waals complementary barrier structure, wherein the detector structure comprises a P-type Si substrate, a SiO2 dielectric layer, a black phosphorus absorption layer, a molybdenum disulfide hole barrier, and a metal source and drain electrode, wherein the Schottky barrier between the metal drain electrode and the black phosphorus layer is designed as an electron barrier. The device preparation steps are to sequentially transfer the mechanically stripped black phosphorus and molybdenum disulfide to a substrate having a dielectric layer, use processes such as electron beam exposure and thermal evaporation to make a metal source electrode on the molybdenum disulfide, and finally transfer the customized transfer electrode to the molybdenum disulfide layer to make a metal source electrode. A vertical van der Waals complementary barrier infrared photodetector is formed. Utilizing the rich band structure and unique physical properties of two-dimensional materials, a complementary barrier band structure is designed, which can effectively suppress dark current, thereby realizing room temperature blackbody detection, polarization detection and gas detection in the medium-wave infrared. The detector has the characteristics of low dark current, room temperature operation, medium-wave infrared response, high sensitivity, fast response and blackbody detection.

[0066] The complementary barrier structure designed based on two-dimensional materials eliminates lattice matching considerations and allows for high-quality interfaces between materials. Furthermore, compared to asymmetric barrier structures and junction-type devices, the complementary barrier mechanism achieves lower dark current at the same temperature. The infrared photodetector constructed from molybdenum disulfide and black phosphorus exhibits a unique band structure. Gold and black phosphorus form an electron barrier, while molybdenum disulfide forms a hole barrier. This unique complementary barrier band structure effectively reduces surface leakage and diffusion currents without suppressing photocurrent. The electron barrier formed by gold and black phosphorus, combined with the n-type doped barrier layer (hole barrier), introduces a space charge region, which imparts photovoltaic properties to the device. Using narrow-bandgap black phosphorus as the absorption layer, it achieves a wide spectral response in the mid-wave infrared and polarization-based detection with a high extinction ratio. The complementary barrier structure enables highly sensitive room-temperature blackbody and gas detection, with a response rate of 51 microseconds at 1060 nm.

[0067] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. Van der Waals complementary barrier structure infrared detector, characterized in that, The structure of the detector is: The P-type Si substrate serves as the base of the detector; A SiO2 dielectric layer is grown on a P-type Si substrate; The black phosphorus layer covers the SiO2 dielectric layer and acts as a conductive channel; One end of the molybdenum disulfide layer covers one end of the black phosphorus layer, and the other end is located on the SiO2 dielectric layer; A drain electrode is directly prepared on the other end of the black phosphorus layer and contacts the black phosphorus layer, wherein the drain electrode is an Au electrode; The source electrode is prepared at the other end of the molybdenum disulfide layer that does not overlap with the black phosphorus layer, and electrical connection is achieved through the overlapping of the molybdenum disulfide layer and the black phosphorus layer.

2. The infrared detector of the van der Waals complementary barrier structure according to claim 1, characterized in that: The P-type Si substrate is a P-type heavily doped Si substrate.

3. The infrared detector of the van der Waals complementary barrier structure according to claim 1, characterized in that: The Au electrode has a thickness of 50 nm on the black phosphorus layer; The source electrode is a Cr and Au electrode, the thickness of Cr on the molybdenum disulfide layer is 10 nanometers, and the thickness of Au on the Cr is 90 nanometers.

4. The infrared detector of the van der Waals complementary barrier structure according to claim 1, wherein: The thickness of the SiO2 dielectric layer is 285 nanometers; The thickness of the black phosphorus layer is 40 to 50 nanometers; The thickness of the molybdenum disulfide layer is 15 to 30 nanometers.

5. The method for preparing an infrared detector having a van der Waals complementary barrier structure according to any one of claims 1 to 4, wherein: The following steps are involved: 1) Mechanically peeling off the black phosphorus layer from the black phosphorus bulk material and transferring it onto the SiO2 dielectric layer; 2) The MoS2 layer is peeled off from the MoS2 bulk material by mechanical exfoliation and transferred to one end of the black phosphorus layer by micro-area fixed-point transfer; 3) Depositing chromium and gold source electrodes on one end of the pre-transferred MoS2 layer using electron beam lithography, thermal evaporation, and lift-off processes; 4) A customized transfer electrode gold is transferred to the surface of the black phosphorus layer through the micro-area fixed-point transfer method to form a drain.

6. Use of an infrared detector having a van der Waals complementary barrier structure according to any one of claims 1 to 4, characterized in that: It is used to realize infrared imaging, gas detection and polarization resolution in the same device.

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