Terahertz photoelectric detector based on graphene nickel telluride heterostructure and preparation method thereof

Abstract

The invention relates to a terahertz photoelectric detector based on a graphene nickel telluride heterostructure and a preparation method of the terahertz photoelectric detector, the terahertz photoelectric detector comprises three layers of materials including upper layer graphene, nickel telluride and lower layer graphene in sequence from top to bottom to form a heterojunction, and multi-path current collection is realized through a four-end metal electrode. The preparation method comprises the following steps: photoetching a four-terminal electrode structure through an ultraviolet lithography technology, then obtaining a four-terminal metal electrode through electron beam evaporation, and obtaining the graphene nickel telluride heterostructure through a mechanical exfoliation method. The device is novel in structure, works at room temperature, is wide in response frequency band, and is suitable for scenes of 6G communication, non-contact imaging, terahertz spectrum detection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz detection devices, and in particular to a terahertz photoelectric detector based on a graphene nickel telluride heterostructure and a preparation method thereof. Background Art

[0002] Terahertz (THz) electromagnetic waves, characterized by their non-ionizing properties, excellent penetrability, and vast bandwidth, are at the forefront of next-generation wireless communications, image perception, security detection, and space exploration. In particular, in future 6G and intelligent systems, there is an urgent need for highly sensitive, broadband, low-power THz detectors capable of operating at room temperature.

[0003] However, traditional terahertz detectors, such as Schottky diodes, superconducting mixers (SISs), and thermal electron detectors, have varying degrees of limitations in terms of device size, operating temperature, and response speed. For example, while superconducting mixers offer high sensitivity, they must operate at low temperatures, limiting their practicality. Detectors based on traditional semiconductor materials are limited in their response bandwidth and nonlinear performance.

[0004] In recent years, topological semimetals, known for their unique electronic structures and excellent transport properties, have become a hot topic in terahertz detection research. Among them, nickel telluride (NiTe2), a typical type-II Dirac semimetal, exhibits rich surface states, spin-momentum locking, and excellent nonlinear response. Meanwhile, graphene, a zero-bandgap two-dimensional material with high carrier mobility and excellent photoelectric response, is suitable for use as a conductive channel or interface control layer in detectors.

[0005] Although there are existing terahertz detector design schemes for graphene or topological semimetal materials in the existing technology, most of them are limited by problems such as a single detection mechanism, a single response path, and poor perception of weak signals. It is difficult to simultaneously realize the coupling utilization of photothermoelectric effect and surface state scattering effect on the same platform, which limits the multifunctional integration capability of the device. Summary of the Invention

[0006] The purpose of the present invention is to provide a terahertz photodetector based on a graphene nickel telluride heterostructure and a preparation method thereof, which solves the problems that most existing technologies are limited to a single detection mechanism, a single response path, poor perception of weak signals, difficulty in simultaneously realizing the coupled utilization of photothermoelectric effect and surface state scattering effect on the same platform, and limiting the multifunctional integration capability of the device.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A terahertz photodetector based on a graphene-nickel telluride heterostructure comprises a base layer composed of intrinsic high-resistance silicon and silicon dioxide, and an absorption layer disposed on the base layer, the absorption layer comprising a four-terminal metal electrode, and a lower graphene layer, a middle nickel telluride layer, and an upper graphene layer alternately stacked from bottom to top; the four-terminal metal electrode comprises a first butterfly-shaped electrode, a second butterfly-shaped electrode, and a first linear electrode and a second linear electrode symmetrically arranged in pairs; the lower graphene layer covers the first butterfly-shaped electrode and the second butterfly electrode, the middle nickel telluride layer covers the lower graphene layer and the first linear electrode, and the upper graphene layer covers the middle nickel telluride layer and the second linear electrode; the lower graphene layer, the middle nickel telluride layer, and the upper graphene layer are alternately stacked to form a heterojunction.

[0009] In the base layer, silicon dioxide covers the intrinsic high-resistance silicon, the resistivity of the intrinsic high-resistance silicon is greater than or equal to 20,000Ω·cm, and the thickness is 400-500μm; the thickness of the silicon dioxide layer is 400-500nm.

[0010] The four-terminal metal electrode is a metal composite electrode, the lower metal layer is chromium with a thickness of 10 nm, and the upper metal layer is gold with a thickness of 20 nm.

[0011] The lower graphene layer is a graphene nanosheet with a thickness of 10-50 nm; the middle nickel telluride layer is a nickel telluride nanosheet with a thickness of 50-100 nm; and the upper graphene layer is a graphene nanosheet with a thickness of 10-50 nm.

[0012] The method for preparing the terahertz photoelectric detector comprises the following steps:

[0013] S1, preparing a four-terminal metal electrode on the substrate layer; photolithography the four-terminal electrode structure, then using an electron beam evaporation process to first evaporate metal chromium, then evaporate metal gold, and finally using a lift-off process to obtain the four-terminal metal electrode; the four-terminal metal electrode includes a first butterfly-shaped electrode, a second butterfly-shaped electrode, and a first linear electrode and a second linear electrode that are symmetrically arranged in pairs;

[0014] S2, preparing and transferring the lower layer of graphene; obtaining nanometer-thick graphene sheets from the single crystal graphene by mechanical exfoliation, and then transferring the graphene nanosheets to the first butterfly electrode and the second butterfly electrode;

[0015] S3, preparing and transferring the middle layer of nickel telluride; obtaining nanometer-thick nickel telluride nanosheets from the single crystal nickel telluride by mechanical exfoliation, and then transferring the nickel telluride material to the first linear electrode and the lower graphene sheet;

[0016] S4, preparing and transferring an upper layer of graphene, obtaining nanometer-thick graphene flakes from the single-crystalline graphene by mechanical exfoliation, and then transferring the graphene nanoflakes to the middle layer of nickel telluride flakes and the second linear electrode;

[0017] S5, fixing the device prepared in steps S1-S4 to the PCB base, completing simple packaging through an ultrasonic lead process, and finally obtaining a terahertz photodetector based on a graphene nickel telluride heterostructure.

[0018] In step S1, a four-terminal electrode structure is formed by photolithography using ultraviolet photolithography technology.

[0019] In the four-terminal metal electrode in step S1 , the thickness of the metal chromium is 10 nm, and the thickness of the metal gold is 20 nm.

[0020] The mechanical stripping in steps S2, S3, and S4 is performed using blue tape.

[0021] The thickness of the lower graphene layer is 10-50 nm; the thickness of the middle nickel telluride layer is 50-100 nm; and the thickness of the upper graphene layer is 10-50 nm.

[0022] The advantages of the present invention are: 1. The present invention uses multi-layer two-dimensional materials to construct a heterostructure to achieve a terahertz photodetector with high sensitivity, broadband response and room temperature operation, and provides a scalable preparation method thereof; 2. The present invention constructs three different charge transport paths by regulating the hierarchical stacking method and electrode connection strategy of the heterostructure material, which can realize multiple detection response modes on the same device platform, effectively improving the photoelectric conversion efficiency and terahertz response sensitivity of the device, and is particularly suitable for terahertz signal detection requirements under broadband, weak signal and room temperature conditions; 3. Through the careful design of the electrode layout and material stacking method in the heterostructure, three different photogenerated carrier transmission paths are realized on the same device platform, namely, a butterfly electrode path, a linear electrode path and a butterfly-linear electrode path, thereby having multimodal detection capabilities. This multi-path design enables the device to respond flexibly according to different incident conditions, effectively expanding its adaptability and functional diversity in complex application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a schematic longitudinal section of the terahertz photodetector of the present invention;

[0024] Figure 2 1 is a schematic top view of the structure of the terahertz photodetector of the present invention;

[0025] Figure 3 This is a simplified diagram of the exploded structure of the terahertz photoelectric detector of the present invention;

[0026] Figure 4 are current-voltage diagrams of three paths of the terahertz photodetector of the present invention;

[0027] Figure 5The photocurrent response spectra of the three paths of the terahertz photodetector of the present invention to different frequencies are shown;

[0028] Figure 6 1 is the photocurrent response spectrum of the three paths of the terahertz photodetector of the present invention under different bias voltages;

[0029] Figure 7 1 is a graph showing variations in optical noise equivalent power versus frequency for three paths of the terahertz photodetector of the present invention;

[0030] Figure 8 1 is a time diagram of the response of three paths of the terahertz photodetector of the present invention to terahertz waves;

[0031] In the figure: 1-intrinsic high-resistance silicon; 2-silicon dioxide; 31-first butterfly-shaped electrode; 32-second butterfly-shaped electrode; 33-first linear electrode; 34-second linear electrode; 4-lower layer graphene; 5-middle layer nickel telluride; 6-upper layer graphene. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings, which are for illustrative purposes only and are not to be construed as limiting the present invention.

[0033] To more concisely illustrate this embodiment, some components well known to those skilled in the art but not relevant to the main content of this invention may be omitted from the drawings or descriptions. In addition, for ease of description, some components may be omitted, enlarged, or reduced in size in the drawings, but they do not represent the dimensions or entire structure of the actual product.

[0034] The present invention discloses a terahertz photodetector based on a graphene nickel telluride heterostructure, which is a multimodal terahertz photodetector based on a graphene nickel telluride heterostructure. Figure 1-3 As shown, a base layer composed of intrinsic high-resistance silicon 1 and silicon dioxide 2 is selected, and the silicon dioxide 2 covers the intrinsic high-resistance silicon 1. The resistivity of the intrinsic high-resistance silicon 1 is greater than or equal to 20,000Ω·cm, and the thickness is 400-500μm; the thickness of the silicon dioxide layer 2 is 400-500nm.

[0035] As well as Figure 1 、 Figure 3 The absorption layer is provided on the substrate layer, and the absorption layer includes a four-terminal metal electrode and a lower layer of graphene 4, a middle layer of nickel telluride 5 and an upper layer of graphene 6 that are alternately stacked from bottom to top. Figure 2 、 Figure 3As shown, the four-terminal metal electrode includes a first butterfly electrode 31, a second butterfly electrode 32, a first linear electrode 33, and a second linear electrode 34, which are symmetrically arranged in pairs; the four-terminal metal electrode is a metal composite electrode, the lower metal is chromium with a thickness of 10nm, and the upper metal is gold with a thickness of 20nm.

[0036] like Figure 2 、 Figure 3 As shown, a lower graphene layer 4 overlies a first butterfly-shaped electrode 31 and a second butterfly-shaped electrode 32, a middle nickel telluride layer 5 overlies the lower graphene layer 4 and the first linear electrode 33, and an upper graphene layer 6 overlies the middle nickel telluride layer 5 and the second linear electrode 34. The lower graphene layer 4, the middle nickel telluride layer 5, and the upper graphene layer 6 are stacked in an alternating pattern to form a heterojunction, which enables multipath current collection via four-terminal metal electrodes.

[0037] Preferably, the lower graphene layer 4 is a graphene nanosheet with a thickness of 10-50 nm; the middle nickel telluride layer 5 is a nickel telluride nanosheet with a thickness of 50-100 nm; and the upper graphene layer 6 is a graphene nanosheet with a thickness of 10-50 nm.

[0038] The method for preparing the terahertz photoelectric detector described above comprises the following steps:

[0039] S1. Prepare a four-terminal metal electrode on the substrate layer; use ultraviolet photolithography technology to photolithograph the four-terminal electrode structure, then use electron beam evaporation process to first evaporate metal chromium with a thickness of 10nm, then evaporate metal gold with a thickness of 20nm, and finally obtain the four-terminal metal electrode through a stripping process; the four-terminal metal electrode includes a first butterfly electrode 31, a second butterfly electrode 32 and a first linear electrode 33 and a second linear electrode 34, which are symmetrically arranged in pairs.

[0040] S2, preparing and transferring the lower layer of graphene 4; using blue tape to mechanically exfoliate the single crystal graphene to obtain a nanometer-thick graphene sheet with a thickness of 10-50 nm, and then transferring the graphene nanosheet to the first butterfly electrode 31 and the second butterfly electrode 32;

[0041] S3, preparing and transferring the middle layer of nickel telluride 5; using blue tape to mechanically exfoliate the single crystal nickel telluride to obtain nanometer-thick nickel telluride nanosheets with a thickness of 50-100 nm, and then transferring the nickel telluride material to the first linear electrode 33 and the lower graphene 4 sheet;

[0042] S4, preparing and transferring the upper graphene 6, using blue tape for mechanical exfoliation, obtaining nanometer-thick graphene flakes with a thickness of 10-50 nm from the single-crystalline graphene, and then transferring the graphene nanoflakes to the middle nickel telluride 5 flakes and the second linear electrode 34;

[0043] S5, fixing the device prepared in steps S1-S4 to the PCB base, connecting the electrode plate of the terahertz photodetector to the lead electrode on the PCB board through an ultrasonic lead process, completing a simple package, and finally obtaining a terahertz photodetector based on a graphene nickel telluride heterostructure.

[0044] The specific embodiments are as follows:

[0045] The present invention is a multimodal terahertz photodetector based on a graphene-nickel telluride heterostructure. It utilizes a microwave source with a nine-fold frequency module to output terahertz waves, a preamplifier to amplify the signal, and a lock-in amplifier to extract the terahertz signal detected by the multimodal terahertz photodetector. All measurements were performed at room temperature.

[0046] Figure 4 The current-voltage diagram of the three paths of the terahertz photodetector of the present invention is shown, with the horizontal axis representing voltage in V and the vertical axis representing current in mA. According to the formula R=V / I, the resistance of the linear electrode path is approximately 1900Ω, the resistance of the butterfly electrode path is approximately 1450Ω, and the resistance of the butterfly-linear electrode path is approximately 3780Ω.

[0047] Figure 5 The photocurrent response spectra of the three paths of the terahertz photodetector of the present invention to different frequencies are shown. The horizontal axis is the frequency of the terahertz wave, in THz, and the vertical axis is the photocurrent generated by the terahertz detector to the terahertz wave, in nA.

[0048] Figure 6 The photocurrent response spectra of the three paths of the terahertz photodetector of the present invention at different bias voltages are shown. The horizontal axis represents the bias voltage in millivolts, and the vertical axis represents the photocurrent generated by the terahertz detector in response to terahertz waves in nanoamps. The device photocurrent responses for the three paths exhibit linear dependence on the bias voltage.

[0049] Figure 7 A graph showing the optical noise equivalent power of three paths in the terahertz photodetector of the present invention as a function of frequency is shown. The horizontal axis represents frequency in THz, and the vertical axis represents the noise equivalent power of the terahertz detector in W / Hz1 / 2. The noise equivalent power is defined as the minimum detectable power when the signal-to-noise ratio is 1.

[0050] Figure 8 This graph shows the response time of three paths of the terahertz photodetector of the present invention to terahertz waves. The horizontal axis is time (in nanoseconds), and the vertical axis is photocurrent. According to the definition of response time, the rise time is the time it takes for the signal to rise from 10% to 90% of the maximum signal, and the fall time is the time it takes for the signal to fall from 90% to 10% of the maximum signal.

[0051] Through precise design of the electrode structure and material hierarchy, the terahertz photodetector of this invention can form three different charge transport pathways on the same platform, thereby supporting multiple photoelectric response mechanisms. The terahertz photodetector of this invention exhibits excellent photoelectric response characteristics, low-noise equivalent power, and fast response time near 0.3 THz, making it suitable for scenarios such as 6G communications, contactless imaging, and terahertz spectroscopy.

[0052] 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 of the present invention should fall within the technical scope of the present invention.

Claims

1. A terahertz photodetector based on a graphene nickel telluride heterostructure, comprising a substrate layer composed of intrinsic high-resistance silicon (1) and silicon dioxide (2), and an absorption layer disposed on the substrate layer, the absorption layer comprising a four-terminal metal electrode, and a lower layer of graphene (4), a middle layer of nickel telluride (5), and an upper layer of graphene (6) alternately stacked from bottom to top; characterized in that: The four-terminal metal electrodes include a first butterfly-shaped electrode (31), a second butterfly-shaped electrode (32), a first linear electrode (33), and a second linear electrode (34) symmetrically arranged in pairs; a lower layer of graphene (4) covers the first butterfly-shaped electrode (31) and the second butterfly-shaped electrode (32); a middle layer of nickel telluride (5) covers the lower layer of graphene (4) and the first linear electrode (33); and an upper layer of graphene (6) covers the middle layer of nickel telluride (5) and the second linear electrode (34); the lower layer of graphene (4), the middle layer of nickel telluride (5), and the upper layer of graphene (6) are stacked in an alternating manner to form a heterojunction.

2. The terahertz photodetector according to claim 1, wherein: In the base layer, silicon dioxide (2) covers the intrinsic high-resistance silicon (1), the intrinsic high-resistance silicon (1) has a resistivity greater than or equal to 20,000Ω·cm and a thickness of 400-500μm; the thickness of the silicon dioxide layer (2) is 400-500nm.

3. The terahertz photodetector according to claim 1, wherein: The four-terminal metal electrode is a metal composite electrode, the lower metal layer is chromium with a thickness of 10 nm, and the upper metal layer is gold with a thickness of 20 nm.

4. The terahertz photodetector according to claim 1, wherein: The lower layer graphene (4) is a graphene nanosheet with a thickness of 10-50 nm; the middle layer nickel telluride (5) is a nickel telluride nanosheet with a thickness of 50-100 nm; and the upper layer graphene (6) is a graphene nanosheet with a thickness of 10-50 nm.

5. The method for preparing a terahertz photodetector according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, preparing a four-terminal metal electrode on a substrate layer; photolithography of the four-terminal electrode structure, then first evaporating metal chromium by electron beam evaporation process, then evaporating metal gold, and finally performing a stripping process to obtain the four-terminal metal electrode; the four-terminal metal electrode includes a first butterfly-shaped electrode (31), a second butterfly-shaped electrode (32), a first linear electrode (33), and a second linear electrode (34) symmetrically arranged in pairs; S2, preparing and transferring a lower layer of graphene (4); obtaining a nanometer-thick graphene sheet from the single-crystal graphene by mechanical exfoliation, and then transferring the graphene nanosheet to the first butterfly electrode (31) and the second butterfly electrode (32); S3, preparing and transferring the middle layer of nickel telluride (5); obtaining nanometer-thick nickel telluride nanosheets from the single crystal nickel telluride by mechanical exfoliation, and then transferring the nickel telluride material to the first linear electrode (33) and the lower layer of graphene (4) sheet; S4, preparing and transferring an upper layer of graphene (6), obtaining a nanometer-thick graphene sheet from the single crystal graphene by mechanical exfoliation, and then transferring the graphene nanosheet to the middle layer of nickel telluride (5) sheet and the second linear electrode (34); S5, fixing the device prepared in steps S1-S4 to the PCB base, completing simple packaging through an ultrasonic lead process, and finally obtaining a terahertz photodetector based on a graphene nickel telluride heterostructure.

6. The method for preparing a terahertz photodetector according to claim 5, wherein: In step S1, a four-terminal electrode structure is formed by photolithography using ultraviolet photolithography technology.

7. The method for preparing a terahertz photodetector according to claim 5, wherein: In the four-terminal metal electrode in step S1 , the thickness of the metal chromium is 10 nm, and the thickness of the metal gold is 20 nm.

8. The method for preparing a terahertz photodetector according to claim 5, wherein: The mechanical stripping in steps S2, S3, and S4 is performed using blue tape.

9. The method for preparing a terahertz photodetector according to claim 8, wherein: The thickness of the lower graphene layer (4) is 10-50 nm; the thickness of the middle nickel telluride layer (5) is 50-100 nm; and the thickness of the upper graphene layer (6) is 10-50 nm.

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