Terahertz self-driven detector

Abstract

The invention discloses a terahertz self-driven detector, and relates to the technical field of terahertz detection. The oxide layer is fixedly arranged on the upper surface of the high-resistance silicon substrate; the PN heterojunction is fixedly arranged on one side, far away from the high-resistance silicon substrate, of the oxide layer; the positive electrode is positioned on the oxide layer and is in contact with one end of the PN heterojunction; the negative electrode is located on the oxide layer and makes contact with the end, away from the positive electrode, of the PN heterojunction. The terahertz self-driven detector provided by the invention is simple in manufacturing process and high in response speed.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz detection, and particularly to a terahertz self-driven detector. Background Art

[0002] Terahertz refers to electromagnetic waves with a frequency of 0.1 - 1 THz, corresponding to an energy in the meV order of magnitude, located between the infrared and microwave frequency bands, and is a transitional stage from photonics to electronics. Existing terahertz room-temperature self-driven detectors mainly include photothermal detectors based on the Seebeck effect, field-effect transistors based on the plasma-assisted detection mechanism, and Schottky detectors based on Schottky barriers. Among them, photothermal detectors have a long response time due to the limitation of photo-thermal-electric conversion, so they are not applicable; the device designs of field-effect transistors and Schottky detectors need to match the frequency of the incident terahertz wave, and the manufacturing requirements are high, so they are also not applicable.

[0003] Therefore, there is an urgent need to design a terahertz detection solution with a simple manufacturing process and a fast response speed. Summary of the Invention

[0004] The purpose of the present invention is to provide a terahertz self-driven detector to solve the problems existing in the above-mentioned prior art, with a simple manufacturing process and a fast response speed.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] The present invention provides a terahertz self-driven detector, including:

[0007] A high-resistance silicon substrate;

[0008] An oxide layer fixedly arranged on the upper surface of the high-resistance silicon substrate;

[0009] A PN heterojunction fixedly arranged on the side of the oxide layer away from the high-resistance silicon substrate;

[0010] A positive electrode located on the oxide layer and in contact with one end of the PN heterojunction;

[0011] A negative electrode located on the oxide layer and in contact with the end of the PN heterojunction away from the positive electrode.

[0012] Preferably, the PN heterojunction includes an N-type semiconductor material layer and a P-type semiconductor material layer, one end of the N-type semiconductor material layer and one end of the P-type semiconductor material layer are stacked up and down; the end of the N-type semiconductor material layer away from the stacking position is in contact with the negative electrode, and the end of the P-type semiconductor material layer away from the stacking position is in contact with the positive electrode.

[0013] Preferably, the positive electrode is a butterfly-shaped positive electrode, and the negative electrode has the same structure as the positive electrode.

[0014] Preferably, the thickness of the high-resistivity silicon substrate is 500 μm.

[0015] Preferably, the oxide layer is made of silicon dioxide.

[0016] Preferably, the positive electrode is made of chromium and gold, and the negative electrode has the same material as the positive electrode.

[0017] Preferably, the PN heterojunction is made of two-dimensional materials.

[0018] Preferably, the resistivity of the high-resistivity silicon substrate is greater than 10000 Ω·cm.

[0019] Preferably, the thickness of the oxide layer is 300 nm.

[0020] Preferably, the positive electrode includes a chromium layer with a thickness of 15 nm, and a gold layer with a thickness of 45 nm is provided on the chromium layer; the negative electrode has the same structure as the positive electrode.

[0021] The present invention has achieved the following technical effects compared with the prior art:

[0022] The present invention realizes room-temperature terahertz self-driven detection based on the combined action of the photovoltaic effect and the electromagnetic-induced potential well effect of the PN heterojunction. By constructing a metal-PN heterojunction-metal structure and utilizing the combined action of the electromagnetic-induced potential well effect and the built-in electric field of the PN heterojunction, a potential well is induced in the PN heterojunction by terahertz light, enabling electrons in the metal to be injected into the PN heterojunction and quickly separated under the action of the built-in electric field, thus realizing room-temperature terahertz self-driven detection of the PN heterojunction. This detector breaks through the limitation of the existing PN heterojunction room-temperature intrinsic thermal excitation, and has the advantages of low power consumption, fast response speed, simple manufacturing process, and easy integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a top view schematic diagram of the terahertz self-driven detector in one or some embodiments of the present invention;

[0025] Figure 2 It is a front view of the terahertz self-driven detector in one or some embodiments of the present invention;

[0026] Figure 3 Schematic diagram of the responsivity of the terahertz self-driven detector in one or some embodiments of the present invention;

[0027] Figure 4 Schematic diagram of the response time of the terahertz self-driven detector in one or some embodiments of the present invention.

[0028] Description of reference numerals: 1 - high-resistance silicon substrate, 2 - oxide layer, 3 - N-type semiconductor material layer, 4 - P-type semiconductor material layer, 5 - positive electrode, 6 - negative electrode. Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] The purpose of the present invention is to provide a terahertz self-driven detector to solve the problems existing in the above-mentioned prior art, with simple manufacturing process and fast response speed.

[0031] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0032] Two-dimensional material detectors based on the photovoltaic effect have the advantages of simple manufacturing and fast response speed. For example, PN heterojunction detectors. The photovoltaic effect refers to the phenomenon that semiconductor materials generate electromotive force and current under light irradiation. When sunlight shines on the PN heterojunction of a semiconductor material, photons are absorbed by the semiconductor material, causing electrons to transition from the valence band to the conduction band, generating electron-hole pairs. Under the action of the PN heterojunction electric field, electrons and holes move in opposite directions respectively to form a current. For a PN heterojunction, due to the different band gaps of the two semiconductor materials, electrons and holes are more likely to be separated at the interface, thus improving the efficiency of the photovoltaic effect; however, because the photon energy in the terahertz band is low, it is difficult for the band gap of the two-dimensional material of the PN heterojunction to match it, and affected by intrinsic thermal excitation, the existing PN heterojunctions cannot achieve terahertz detection at room temperature. Based on this, the present invention provides a terahertz self-driven detector, which can achieve terahertz detection of PN heterojunctions at room temperature, such as Figure 1 and Figure 2As shown, its structure includes a high-resistance silicon substrate 1 with a thickness of 500 μm and a resistivity greater than 10,000 Ω·cm. On the upper surface of the high-resistance silicon substrate 1, there is an oxide layer 2 made of silicon dioxide with a thickness of 300 nm; on the oxide layer 2, there are a positive electrode 5, a PN heterojunction, and a negative electrode 6; the positive electrode 5 is in contact with one end of the PN heterojunction; the negative electrode 6 is in contact with the end of the PN heterojunction far from the positive electrode 5. The present invention is based on the electromagnetic induction potential well effect. The electromagnetic induction potential well effect refers to that when electromagnetic waves irradiate a metal-semiconductor-metal structure, an induced potential well will be generated in the semiconductor, and this potential well can capture and bind electrons, thereby changing the electrical properties of the material. In the present invention, the semiconductor uses a PN heterojunction, and the metal uses the positive electrode 5 and the negative electrode 6. By constructing a metal-PN heterojunction-metal structure, using the combined action of the electromagnetic induction potential well effect and the built-in electric field of the PN heterojunction based on the photovoltaic effect, a potential well is induced in the PN heterojunction by terahertz light, so that the electrons in the positive electrode 5 and the negative electrode 6 are injected into the PN heterojunction and quickly separated under the action of the built-in electric field, and the responsivity to 0.17 THz at zero bias is 9.9×10 5 V / W, realizing terahertz self-driven detection at room temperature of the PN heterojunction.

[0033] In one embodiment, the PN heterojunction is made of a two-dimensional material, including an N-type semiconductor material layer 3 and a P-type semiconductor material layer 4. One end of the N-type semiconductor material layer 3 and one end of the P-type semiconductor material layer 4 are stacked vertically; a two-dimensional material refers to a material in which electrons can only move freely in two dimensions, usually only one or a few atomic layers thick, such as graphene, molybdenum disulfide, etc.; the specific material of the PN heterojunction in the present invention is not limited, and in other embodiments, it can also be made of materials such as germanium, silicon, cadmium selenide, etc.; the end of the N-type semiconductor material layer 3 far from the stacking position is in contact with the negative electrode 6, and the end of the P-type semiconductor material layer 4 far from the stacking position is in contact with the positive electrode 5. The positive electrode 5 is a butterfly-shaped positive electrode, and the positive electrode 5 includes a chromium layer with a thickness of 15 nm, and a gold layer with a thickness of 45 nm is provided on the chromium layer; the structure and material of the negative electrode 6 and the positive electrode 5 are the same, and the two are symmetrically arranged at both ends of the PN heterojunction.

[0034] Example 1

[0035] The terahertz self-driven detector of this embodiment uses a high-resistance silicon substrate 1 with a thickness of 500 μm and a resistivity greater than 10,000 Ω·cm. There is a 300-nm-thick silicon dioxide layer on the high-resistance silicon substrate 1. A 100-nm-thick N-type semiconductor material layer 3 PdSe2 is transferred onto the silicon dioxide layer by mechanical exfoliation. Then, a 150-nm-thick P-type semiconductor material layer 4 MoTe2 is mechanically exfoliated using PDMS. The selected two-dimensional material is transferred onto PdSe2 using a two-dimensional material transfer platform. By means of ultraviolet lithography and dual ion beam sputtering, a butterfly-shaped positive electrode and a butterfly-shaped negative electrode are respectively prepared at one end of the P-type semiconductor material layer 4 and the N-type semiconductor material layer 3. The distance between the butterfly-shaped positive electrode and the butterfly-shaped negative electrode is the length of the PN heterojunction sensitive element, and this length is 5 μm. The widths of the butterfly-shaped positive electrode and the butterfly-shaped negative electrode in contact with the PN heterojunction sensitive element are 5 μm.

[0036] Embodiment 2

[0037] The terahertz self-driven detector of this embodiment uses a high-resistance silicon substrate 1 with a thickness of 500 μm and a resistivity greater than 10,000 Ω·cm. There is a 300-nm-thick silicon dioxide layer on the high-resistance silicon substrate 1. A 150-nm-thick N-type semiconductor material layer 3 PdSe2 is transferred onto the silicon dioxide layer by mechanical exfoliation. Then, a 150-nm-thick P-type semiconductor material layer 4 MoTe2 is mechanically exfoliated using PDMS. The set two-dimensional material is transferred onto PdSe2 using a two-dimensional material transfer platform. By means of ultraviolet lithography and dual ion beam sputtering, a butterfly-shaped positive electrode and a butterfly-shaped negative electrode are respectively prepared at one end of the P-type semiconductor material layer 4 and the N-type semiconductor material layer 3. The distance between the butterfly-shaped positive electrode and the butterfly-shaped negative electrode is the length of the PN heterojunction sensitive element, and this length is 5 μm. The widths of the butterfly-shaped positive electrode and the butterfly-shaped negative electrode in contact with the PN heterojunction sensitive element are 5 μm.

[0038] Embodiment 3

[0039] The terahertz self-driven detector of this embodiment uses a high-resistance silicon substrate 1 with a thickness of 500 μm and a resistivity greater than 10,000 Ω·cm. There is a 300-nm-thick silicon dioxide layer on the high-resistance silicon substrate 1. A 200-nm-thick N-type semiconductor material layer 3 PdSe2 is transferred onto the silicon dioxide layer by mechanical exfoliation. Then, a 100-nm-thick P-type semiconductor material layer 4 MoTe2 is mechanically exfoliated using PDMS. The set two-dimensional material is transferred onto PdSe2 using a two-dimensional material transfer platform. The butterfly-shaped positive electrode and the butterfly-shaped negative electrode respectively prepared at one end of the P-type semiconductor material layer 4 and the N-type semiconductor material layer 3 by means of ultraviolet lithography and dual ion beam sputtering. The distance between the butterfly-shaped positive electrode and the butterfly-shaped negative electrode is the length of the PN heterojunction sensitive element, and this length is 5 μm. The widths of the butterfly-shaped positive electrode and the butterfly-shaped negative electrode in contact with the PN heterojunction sensitive element are 5 μm.

[0040] The present invention is further described in detail by providing specific experimental steps.

[0041] 1. Preparation of PN Heterojunction Terahertz Room Temperature Self-Powered Detector

[0042] Transfer PdSe2 onto the high-resistivity silicon substrate 1 by mechanical exfoliation method. Then, mechanically exfoliate MoTe2 using PDMS. Select a suitable MoTe2 material using a two-dimensional material transfer platform and transfer it onto PdSe2 to form the required sample. Then, spin-coat the photoresist AZ5214 on this sample. Spin-coating parameters: rotation speed 4000 revolutions per second, time 30 seconds. Then place the sample on a hot plate at 95 °C and dry it for 5 min.

[0043] After drying, use an ultraviolet lithography machine to prepare a butterfly-shaped positive electrode and a butterfly-shaped negative electrode. The specific process is as follows: exposure time 3.5 seconds, development time 9 seconds. After development, place it on a hot plate at 95 °C and dry it for 3 minutes. Then grow 15 nm of Cr and 45 nm of Au by dual ion beam sputtering to form the butterfly-shaped positive electrode and the butterfly-shaped negative electrode. Finally, place the sample in an acetone solution heated to 50 °C, soak it for 1 h, and then strip the excess metal film to form the final terahertz self-powered detector.

[0044] 2. Performance Testing of the Present Invention

[0045] Utilize the response performance of the terahertz self-powered detector of the present invention. The electrically modulated terahertz light source is vertically irradiated on the surface of the terahertz self-powered detector, and the response signal of the terahertz self-powered detector is amplified by a preamplifier and read out by a lock-in amplifier. Figure 3 Under room temperature conditions, when the terahertz self-powered detector is at zero bias, the responsivity at 0.171 THz is 9.9×10 5 V / W. Figure 4 The response time of the terahertz self-powered detector of the present invention is given as 6.6 μs, and the response time is fast.

[0046] Specific examples are applied in the present invention to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A terahertz self-driven detector, characterized in that: Comprising: A high-resistance silicon substrate; An oxide layer fixedly disposed on the upper surface of the high-resistance silicon substrate; A PN heterojunction fixedly disposed on the side of the oxide layer away from the high-resistance silicon substrate; A positive electrode located on the oxide layer and in contact with one end of the PN heterojunction; A negative electrode located on the oxide layer and in contact with the end of the PN heterojunction away from the positive electrode.

2. The terahertz self-driven detector according to claim 1, wherein: The PN heterojunction includes an N-type semiconductor material layer and a P-type semiconductor material layer, and one end of the N-type semiconductor material layer and one end of the P-type semiconductor material layer are stacked vertically; The end of the N-type semiconductor material layer away from the stacking position is in contact with the negative electrode, and the end of the P-type semiconductor material layer away from the stacking position is in contact with the positive electrode.

3. The terahertz self-driven detector according to claim 1, wherein: The positive electrode is a butterfly-shaped positive electrode, and the negative electrode has the same structure as the positive electrode.

4. The terahertz self-powered detector according to claim 1, wherein: The thickness of the high-resistance silicon substrate is 500 μm.

5. The terahertz self-driven detector according to claim 1, characterized in that: The oxide layer is made of silicon dioxide.

6. The terahertz self-powered detector according to claim 1, wherein: The positive electrode is made of chromium and gold, and the negative electrode has the same material as the positive electrode.

7. The terahertz self-powered detector according to claim 1, wherein: The PN heterojunction is made of a two-dimensional material.

8. The terahertz self-powered detector according to claim 1, characterized in that: The resistivity of the high-resistance silicon substrate is greater than 10000 Ω·cm.

9. The terahertz self-powered detector according to claim 1, wherein: The thickness of the oxide layer is 300 nm.

10. The terahertz self-driven detector according to claim 6, characterized in that: The positive electrode includes a chromium layer with a thickness of 15 nm, and a gold layer with a thickness of 45 nm is provided on the chromium layer; the negative electrode has the same structure as the positive electrode.

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