Composite photoelectric detector based on two-dimensional heterojunction and quantum dot material

Abstract

The invention discloses a composite photoelectric detector based on a two-dimensional heterojunction and a quantum dot material, and belongs to the field of photoelectric detection. According to the detector, two two-dimensional materials are overlapped in the vertical direction to form a photovoltaic (PV) type-II type P-N heterojunction in the vertical direction, a quantum dot material is spin-coated at the top end of the heterojunction, and the weak light detection performance of the heterojunction detector is continuously enhanced by utilizing the quantum dot material to generate more photon-generated carriers and the space charge binding capability, so that the detection efficiency of the detector is improved. The cooperation of photogating and PV effects is realized, so that the linear dynamic range of the detector is improved. The structure of the photoelectric detector comprises a metal electrode, a WSe2 two-dimensional material, a MoSe2 two-dimensional material and PbSe2 quantum dots from bottom to top. According to the invention, the top end of the two-dimensional material heterojunction in the vertical direction is spin-coated with the quantum dot material, and the quantum dot material has a good wavelength selective absorption characteristic on incident light, so that the detection of the device on a specific wavelength is enhanced, and the linear dynamic range of the device is improved.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detection, and in particular relates to a composite photoelectric detector based on two-dimensional heterojunction and quantum dot materials. Background Art

[0002] Photodetectors play an extremely important role in daily life and production. Whether used for photoelectric imaging or optical communication, the function of photodetectors is to convert the collected optical signals into electrical signals that can be processed by standard electronic devices. Infrared photodetectors have been the focus of international research due to their wide applications in biological imaging, thermal imaging, health monitoring, night vision and optical communication. Silicon is the most commonly used material in semiconductor optoelectronic devices. Silicon-based photodetectors have a fairly mature process on existing complementary metal oxide semiconductor imaging devices, which makes silicon-based optoelectronic devices scalable while miniaturizing, greatly reducing manufacturing costs. At the same time, they have the characteristics of low power consumption and high efficiency. As the main force of visible light and near-infrared photodetection, they are widely used in aerospace, security inspection, medical treatment, monitoring and other fields. However, since silicon is an indirect bandgap semiconductor material, its bandgap is about 1.12 eV (the corresponding absorption cutoff wavelength is about 1.1μm), which limits the detection of silicon in the near-infrared band. In order to expand the response band of photodetectors, semiconductor materials with smaller band gaps are often needed, such as epitaxially grown HgCdTe, InGaAs, indium antimonide (InSb) and type II superlattices. These semiconductor materials can well cover the near-infrared to far-infrared spectral range that silicon cannot detect, but such materials require the use of equipment such as molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD), which greatly increases the manufacturing cost; secondly, infrared optoelectronic devices prepared from these materials generally need to work at low temperatures to maintain low noise and high sensitivity. At the same time, these traditional infrared semiconductor materials are difficult to be compatible with silicon by relying on mature CMOS processes due to the problem of lattice mismatch, which makes it difficult to integrate them at high density. Traditional photodetection materials have been difficult to meet the requirements of silicon process compatibility, low manufacturing cost, and no need for low temperature operation. Research based on new mechanisms and new materials is a technical problem that needs to be overcome in the development of new high-performance infrared optoelectronic devices.

[0003] In recent years, the emergence of many new confined materials, including two-dimensional, one-dimensional, and zero-dimensional materials, has provided more optimization space for the development of high-performance photoelectric detection technology. Zero-dimensional material quantum dots have narrow emission spectra, very high detection sensitivity, and tunable absorption peaks, showing their huge detection potential. In particular, quantum dots prepared from traditional narrow bandgap semiconductors show excellent performance in the near-infrared band to short-wave infrared range (750nm–3500nm), including materials such as lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), mercury telluride (HgTe), indium arsenide (InAs), and indium telluride (InSb). Inorganic quantum dots have developed rapidly in recent years due to their generally high light absorption, high detection efficiency in the infrared band, low cost, easy preparation, and no restrictions on substrate materials. Compared with other material technologies, quantum dots are very competitive in the development of new infrared optoelectronic devices.

[0004] At present, infrared quantum dot heterojunction photodetectors use quantum dot materials to prepare colloidal films as infrared sensitive layers, and two-dimensional materials such as graphene as conductive channels. The quantum dot materials absorb incident light and generate photogenerated carriers. Electron-hole pairs separate at the two-dimensional / quantum dot interface, and carriers enter the conductive channel graphene to form photocurrent, realizing photodetection. However, due to the high dark current of the device caused by the single two-dimensional material channel, it is easy to annihilate weak light carrier signals, and ordinary heterojunction two-dimensional material devices only use photovoltaic response, and the weak light detection capability is poor, which ultimately limits the linear dynamic range of the photodetector. Summary of the invention

[0005] The purpose of the present invention is to solve the problems that the traditional two-dimensional material heterojunction has poor weak light detection performance, limited photocurrent, and a small linear dynamic range of the photodetector. A composite photodetector based on a two-dimensional material heterojunction and a quantum dot material and a preparation method thereof are proposed.

[0006] The present invention uses two two-dimensional materials to form a heterojunction, and by spin-coating quantum dot materials on the top area of ​​the heterojunction, the quantum dot materials are used to generate more photogenerated carriers and space charge binding capabilities, thereby achieving the synergy of photogating and PV effects and making use of the built-in electric field dark current suppression effect of the two-dimensional heterojunction, continuously enhancing the weak light detection performance of the heterojunction detector, thereby improving the linear dynamic range of the detector.

[0007] Therefore, the technical solution of the present invention is a composite photodetector based on a two-dimensional heterojunction and a quantum dot material, characterized in that the structure of the composite photodetector includes: a positive metal electrode, a negative metal electrode, a WSe2 two-dimensional material, a MoSe2 two-dimensional material, and a PbSe2 quantum dot; The positive metal electrode and the negative metal electrode are made of the same material, and the structure of the entire composite photodetector includes three layers: a bottom layer, a middle layer, and a top layer; the WSe2 two-dimensional material includes two parts, one part is located in the bottom layer, and the other part is located in the middle layer, and the WSe2 two-dimensional materials in the bottom layer and the middle layer are staggered and connected to each other to form a step shape; the bottom layer of the composite photodetector structure includes a positive metal electrode, a negative metal electrode and a part of the WSe2 two-dimensional material, and the WSe2 two-dimensional material in the bottom layer is located between the positive metal electrode and the negative metal electrode, and they do not contact each other; the middle layer includes another part of the WSe2 two-dimensional material and the MoSe2 two-dimensional material, and the WSe2 two-dimensional material in the middle layer is located above the positive metal electrode, and the MoSe2 two-dimensional material is located above the WSe2 two-dimensional material in the bottom layer and the negative metal electrode, and the MoSe2 two-dimensional material and the WSe2 two-dimensional material in the middle layer do not contact in the middle layer space; the PbSe2 quantum dots are located above the MoSe2 two-dimensional material.

[0008] Furthermore, the thickness of the metal electrode is 35-45 nm.

[0009] Furthermore, the thickness of each part of the WSe2 two-dimensional material is 10-20nm.

[0010] Furthermore, the thickness of the MoSe2 two-dimensional material is 20-30nm.

[0011] Furthermore, the thickness of the PbSe2 quantum dots is 300-350 nm.

[0012] The present invention spin-coats quantum dot materials on the top region of a heterojunction composed of two-dimensional materials, utilizes the quantum dot materials to generate more photogenerated carriers and space charge binding capabilities, continuously enhances the weak light detection performance of the heterojunction detector, realizes the synergy of photogating and PV effects, and improves the linear dynamic range of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the side section structure of the detector of the present invention.

[0014] Figure 2 It is a top view of the detector of the present invention.

[0015] Figure 3 It is a bottom view of the detector of the present invention.

[0016] Figure 4 The figure is a comparison chart of the linear dynamic range of the detector of the present invention and the linear dynamic range of a conventional detector (Example 1).

[0017] Figure 5 This is a comparison chart between the linear dynamic range of the detector of the present invention and the linear dynamic range of a conventional detector (Example 2). DETAILED DESCRIPTION

[0018] like Figure 1 Shown: A composite photodetector based on a two-dimensional material heterojunction and quantum dot material, whose structure includes: metal electrodes, WSe2 two-dimensional materials, MoSe2 two-dimensional materials, and PbSe2 quantum dots.

[0019] The metal electrode is on the glass substrate layer; the WSe2 two-dimensional material is on the metal electrode; the MoSe2 two-dimensional material is on the WSe2 two-dimensional material; and the PbSe2 quantum dots are on the MoSe2 two-dimensional material.

[0020] Further, the metal electrode is fabricated on a glass substrate, and the thickness of the metal electrode is 35-45 nm; Furthermore, the WSe2 two-dimensional material is fabricated on a metal electrode, and the thickness of the WSe2 two-dimensional material is 10-20 nm; Furthermore, the MoSe2 two-dimensional material is fabricated on the WSe2 two-dimensional material, and the thickness of the MoSe2 two-dimensional material is 20-30 nm; Furthermore, PbSe2 quantum dots are spin-coated on the MoSe2 two-dimensional material, and the thickness of the PbSe2 quantum dots is 300-350nm.

[0021] A composite photodetector based on a two-dimensional material heterojunction and a quantum dot material of the present invention: S1. Providing a glass substrate; S2. Fabricating a metal electrode on a glass substrate; S3. Fabrication of WSe2 two-dimensional materials on metal electrodes; S4. Fabricating MoSe2 two-dimensional material on WSe2 two-dimensional material; S5. Spin-coat PbSe2 quantum dots on the surface of MoSe2 two-dimensional material.

[0022] Example 1 is a composite photodetector based on a two-dimensional material heterojunction and a quantum dot material provided by the present invention:

[0023] S1, the metal electrode is made on a glass substrate, and the thickness of the metal electrode is 35 nm; S2, WSe2 two-dimensional material is made on the metal electrode, and the thickness of WSe2 two-dimensional material is 10nm; S3, MoSe2 two-dimensional material is made on WSe2 two-dimensional material, and the thickness of MoSe2 two-dimensional material is 20nm; S4, PbSe2 quantum dots are spin-coated on MoSe2 two-dimensional material, and the thickness of PbSe2 quantum dots is 300nm.

[0024] A bias voltage is applied to the metal electrode of the device to put the heterojunction in a reverse bias state. The target light passes through the heterojunction and quantum dots to generate photogenerated carriers. The photogenerated carriers are separated and output from the device under the action of the built-in electric field to form a photocurrent. The incident target light is detected by measuring the photocurrent. In this embodiment, the absorption peak of the PbSe quantum dots is at 1550nm. The linear dynamic range of the photodetector is as follows: Figure 4 As shown, the linear dynamic range of the composite photodetector of the present invention is higher than that of the conventional two-dimensional heterojunction detector. In summary, the linear dynamic range of the composite photodetector in the first embodiment is better than that of the conventional detector.

[0025] Example 2 is a composite photodetector based on a two-dimensional material heterojunction and a quantum dot material provided by the present invention:

[0026] S1, the metal electrode is made on a glass substrate, and the thickness of the metal electrode is 45 nm; S2, WSe2 two-dimensional material is made on the metal electrode, and the thickness of WSe2 two-dimensional material is 20nm; S3, MoSe2 two-dimensional material is made on WSe2 two-dimensional material, and the thickness of MoSe2 two-dimensional material is 30nm; S4, PbSe2 quantum dots are spin-coated on MoSe2 two-dimensional material, and the thickness of PbSe2 quantum dots is 350nm.

[0027] A bias voltage is applied to the metal electrode of the device to put the heterojunction in a reverse bias state. The target light passes through the heterojunction and quantum dots to generate photogenerated carriers. The photogenerated carriers are separated and output from the device under the action of the built-in electric field to form a photocurrent. The incident target light is detected by measuring the photocurrent. In this embodiment, the absorption peak of the PbSe quantum dots is located at 1310nm. The linear dynamic range of the photodetector is as follows: Figure 5 As shown, the linear dynamic range of the composite photodetector of the present invention is higher than that of the conventional two-dimensional heterojunction detector. In summary, the linear dynamic range of the composite photodetector in Example 1 is better than that of the conventional two-dimensional heterojunction detector.

[0028] The materials of quantum dots and two-dimensional materials in the embodiment can be selected and replaced according to actual needs. By overlapping two two-dimensional materials (for example, they can be replaced by MoS2 / WSe2) in the vertical direction, a photovoltaic (PV) type-II PN heterojunction is formed in the vertical direction, and the quantum dot material (which can also be replaced by PbTe or CdTe quantum dots with longer wavelengths) is spin-coated on the top of the heterojunction. The quantum dot material is used to generate more photogenerated carriers and space charge binding capabilities, and the weak light detection performance of the heterojunction detector is continuously enhanced, and the synergy of photogating and PV effects is achieved to improve the linear dynamic range of the detector.

Claims

1. A composite photodetector based on a two-dimensional heterojunction and quantum dot material, characterized in that: The structure of the composite photodetector includes: a positive metal electrode, a negative metal electrode, a WSe2 two-dimensional material, a MoSe2 two-dimensional material, and a PbSe2 quantum dot; The positive metal electrode and the negative metal electrode are made of the same material, and the structure of the entire composite photodetector includes three layers: a bottom layer, a middle layer, and a top layer; the WSe2 two-dimensional material includes two parts, one part is located in the bottom layer, and the other part is located in the middle layer, and the WSe2 two-dimensional materials in the bottom layer and the middle layer are staggered and connected to each other to form a step shape; the bottom layer of the composite photodetector structure includes a positive metal electrode, a negative metal electrode and a part of the WSe2 two-dimensional material, and the WSe2 two-dimensional material in the bottom layer is located between the positive metal electrode and the negative metal electrode, and they do not contact each other; the middle layer includes another part of the WSe2 two-dimensional material and the MoSe2 two-dimensional material, and the WSe2 two-dimensional material in the middle layer is located above the positive metal electrode, and the MoSe2 two-dimensional material is located above the WSe2 two-dimensional material in the bottom layer and the negative metal electrode, and the MoSe2 two-dimensional material and the WSe2 two-dimensional material in the middle layer do not contact in the middle layer space; the PbSe2 quantum dots are located above the MoSe2 two-dimensional material.

2. A composite photodetector based on a two-dimensional heterojunction and quantum dot material as claimed in claim 1, characterized in that: The thickness of the metal electrode is 35-45 nm.

3. A composite photodetector based on a two-dimensional heterojunction and quantum dot material as claimed in claim 1, characterized in that: The thickness of each part of the WSe2 two-dimensional material is 10-20nm.

4. A composite photodetector based on a two-dimensional heterojunction and quantum dot material as claimed in claim 1, characterized in that: The thickness of MoSe2 two-dimensional material is 20-30nm.

5. The composite photodetector based on two-dimensional heterojunction and quantum dot material according to claim 1, characterized in that: The thickness of PbSe2 quantum dots is 300-350nm.

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