Millimeter wave detector and preparation method and application thereof

Abstract

The invention relates to a millimeter wave detector and a preparation method and application thereof.The millimeter wave detector comprises a substrate, a cross-shaped semiconductor structure is arranged on the substrate, a linear double-antenna structure or an orthogonal four-antenna structure is arranged at the end of the cross-shaped semiconductor structure, and a semiconductor wafer is prepared into a cross shape through photoetching, etching and other methods; then depositing a metal antenna at a corresponding position, preparing the millimeter wave detector with high direction selectivity through the steps of standard stripping and the like, and obtaining a detector with high polarization ratio if a linear double-antenna structure is photoetched; if an orthogonal four-antenna structure is photoetched, a detector with a low polarization ratio can be obtained. Compared with the prior art, the high-direction-selectivity designable semiconductor plasmon millimeter wave detector can be conveniently and simply prepared, and the high-direction-selectivity designable semiconductor plasmon millimeter wave detector has good millimeter wave polarization selectivity and sensitivity.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to a millimeter-wave detector, its fabrication method, and its application. Background Technology

[0002] Millimeter-wave detectors are key devices that convert millimeter-wave optical information into electrical signals, and they have wide applications in many fields such as communications, security, biological diagnostics, spectral analysis, and remote sensing. Achieving room-temperature detectors with high directional selectivity, all-angle signal resolution, simple structure, strong design flexibility, high sensitivity, and fast response speed has always been a research focus in this field. Such detectors are also core components of millimeter-wave systems such as communication networks, deep space exploration, security inspection systems, spectrometers, and material composition analysis.

[0003] However, millimeter-wave photons have low energies (e.g., only about 1.24 meV at 0.3 THz), making them highly susceptible to background thermal perturbations (about 25.7 meV at 300 K) at room temperature. Furthermore, the band gap of narrow-bandgap semiconductors is larger than the target photon energy (e.g., the band gap of a typical InSb semiconductor is about 170 meV), making it difficult to apply efficient photoexcitation mechanisms in traditional optoelectronic semiconductors. Currently used detectors include Golay detectors, pyroelectric devices, and calorimeters. Although these technologies have different response mechanisms, they all respond to polarized millimeter-wave unpolarized signals and exhibit poor noise equivalent power (NEP) (Golay and pyroelectric devices have approximately 10 NEP). -9 -10 -10 WHz -0.5 Terahertz (TMW) antennas are characterized by slow response times (Golay, pyroelectric devices, and uncooled microbolometers typically operate on the millisecond scale). Field-effect transistor (FET, HEMT, and MOSFET) technologies require three or more electrode structures, while terahertz photoconductive antennas often require femtosecond lasers to pump high-resistivity, ultra-short carrier lifetime semiconductors, further complicating the detection of millimeter-wave signals. In addition, a range of emerging materials, including black phosphorus, perovskite, carbon nanotubes, Dirac half-metals, topological insulators, and graphene, are also being used for millimeter-wave detection; these devices have a null emission potential (NEP) of approximately 10⁻¹⁰. -12 WHz -0.5 However, more effort is needed to prepare the focal plane array. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a millimeter-wave detector, its fabrication method, and its application. This invention enables the convenient and simple fabrication of a highly directionally selective, designable semiconductor plasmon millimeter-wave detector with excellent millimeter-wave polarization selectivity and sensitivity.

[0005] The objective of this invention can be achieved through the following technical solution: a millimeter-wave detector, including a substrate, wherein a cross-shaped semiconductor structure is provided on the substrate, and a line-shaped dual antenna structure or an orthogonal four antenna structure is provided at the end of the cross-shaped semiconductor structure.

[0006] Furthermore, a transition layer is provided between the substrate and the cross-shaped semiconductor structure, the transition layer including a gradient layer and a barrier layer.

[0007] Furthermore, the cross-shaped semiconductor structure is made of a narrow bandgap semiconductor material, including InSb, InGaAs, or HgTe.

[0008] A method for fabricating a millimeter-wave detector includes the following steps: S1. Etch the epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure, ensuring that there is no semiconductor residue in the etched area; S2. First, deposit a metal layer at the end of the cross-shaped semiconductor structure, and then deposit the target structure and number of metal antennas. S3. The prepared device is cut and bonded to the test base using gold wire bonding.

[0009] Further, step S1 specifically involves using ultraviolet lithography to etch the epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure. The narrow bandgap semiconductor wafer includes a substrate, a gradient layer, a barrier layer, and a narrow bandgap semiconductor active electron layer arranged sequentially from bottom to top.

[0010] Further, step S1 includes the following process: S11. The epitaxially grown narrow bandgap semiconductor wafer is ultrasonically cleaned sequentially with acetone, alcohol and deionized water. S12. Photoresist is uniformly coated on a narrow bandgap semiconductor wafer, and patterning is performed using an ultraviolet lithography machine. The lithographic narrow bandgap semiconductor wafer is then placed in an etching solution for etching, retaining only the central cross-shaped pattern and not etching the barrier layer.

[0011] Furthermore, the etching solution in step S12 includes hydrofluoric acid, hydrogen peroxide, citric acid, and deionized water, and deionized water is used for cleaning after etching is completed.

[0012] Further, step S2 includes the following process: S21. The etched wafer from step S1 is coated with photoresist again and photolithography is performed. S22. For photolithographically etched wafers, deposit titanium and gold thin films using an electron beam evaporation coating equipment for metal thin film growth; S23. After the metal thin film is deposited, a stripping process is performed to obtain the target structure and number of metal antennas.

[0013] Furthermore, the metal antenna has a dipole-like structure, and the total length of the metal antenna is 1 / 2 of the target detection wavelength.

[0014] A millimeter-wave detection method includes the following steps: A1. Fix the millimeter-wave detector in the middle of the rotating bracket that can rotate 360 ​​degrees, and ensure that the rotation center of the millimeter-wave detector and the rotating bracket are on the same horizontal line. A2. Place the centers of the millimeter-wave signal source, chopper, and millimeter-wave detector on the same horizontal line; Connect the millimeter-wave detector to the preamplifier and lock-in amplifier; A3. Rotate the rotating bracket 360 degrees and read the polarization signal data output by the millimeter-wave detector from the lock-in amplifier.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention has a cross-shaped semiconductor structure on the substrate, and a line-shaped dual antenna structure or an orthogonal four antenna structure at the end of the cross-shaped semiconductor structure. When the line-shaped dual antenna structure is used, a high polarization ratio detector can be obtained. When the orthogonal four antenna structure is used, a low polarization ratio detector can be obtained. That is, by optimizing and adjusting the structure and number of metal antennas, polarization detection can be designed and the polarization detection sensitivity is high.

[0016] In this invention, the cross-shaped semiconductor structure uses narrow bandgap semiconductor materials, including InSb, InGaAs, or HgTe. Based on the fact that the narrow bandgap semiconductor, under millimeter-wave irradiation, induces the generation of non-equilibrium electrons using surface plasmon polaritons (SPP), the photocurrent or photovoltage can be read by applying a bias voltage.

[0017] This invention first uses photolithography, etching and other methods to prepare a narrow bandgap semiconductor wafer into a cross-shaped semiconductor structure, then deposits a metal antenna at the corresponding position, and then obtains a high directional selectivity millimeter-wave detector through standard lift-off and other steps. The whole preparation process is simple and convenient and does not require cooling. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a millimeter-wave detector with a linear dual-antenna structure as shown in Example 1. Figure 2 This is a schematic diagram of a millimeter-wave detector using an orthogonal four-antenna structure in Example 1; Figure 3 for Figure 1 The diagram shows the test results of the millimeter-wave detector. Figure 4 for Figure 2 The diagram shows the test results of the millimeter-wave detector. Figure 5 This is a schematic diagram of a millimeter-wave detector with a linear dual-antenna structure as shown in Example 2; Figure 6 This is a schematic diagram of a millimeter-wave detector using an orthogonal four-antenna structure in Example 2; Figure 7 for Figure 5 The diagram shows the test results of the millimeter-wave detector. Figure 8 for Figure 6 The diagram shows the test results of the millimeter-wave detector. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] To address the issue of low polarization sensitivity in existing millimeter-wave photodetectors, this solution proposes a simple, room-temperature-operable millimeter-wave detector with high sensitivity and high responsivity, based on narrow-bandgap semiconductor polypropylene (SPP) and optimized antenna structure and quantity. The detector comprises a substrate on which a cross-shaped semiconductor structure (using a narrow-bandgap semiconductor material, such as InSb, InGaAs, or HgTe) is mounted. A linear dual-antenna structure or an orthogonal four-antenna structure is located at the ends of the cross-shaped semiconductor structure. A transition layer, comprising a gradient layer and a blocking layer, is positioned between the substrate and the cross-shaped semiconductor structure.

[0021] The process of fabricating the above-mentioned millimeter-wave detector includes: S1. Etch the epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure, ensuring that there is no semiconductor residue in the etched area; Specifically, ultraviolet lithography is used to etch an epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure. The narrow bandgap semiconductor wafer includes, from bottom to top, a substrate, a gradient layer, a barrier layer, and a narrow bandgap semiconductor active electron layer, and includes the following processes: S11. The epitaxially grown narrow bandgap semiconductor wafer is ultrasonically cleaned sequentially with acetone, alcohol and deionized water. S12. Photoresist is uniformly coated on a narrow bandgap semiconductor wafer, and patterning is performed using an ultraviolet lithography machine. The lithographic narrow bandgap semiconductor wafer is then placed in an etching solution for etching, retaining only the central cross-shaped pattern and not etching the barrier layer. The etching solution includes hydrofluoric acid, hydrogen peroxide, citric acid, and deionized water. After etching, the wafer is cleaned with deionized water. S2. First, a metal layer is deposited at the end of the cross-shaped semiconductor structure, and then the target structure and number of metal antennas are deposited, including the following processes: S21. The etched wafer from step S1 is coated with photoresist again and photolithography is performed. S22. For photolithographically etched wafers, deposit thin films of titanium and gold using a metal thin film evaporation equipment; S23. After the metal thin film is deposited, it is stripped to obtain the target structure and number of metal antennas. The metal antennas are dipole-like structures and the total length of the metal antennas is 1 / 2 of the target detection wavelength. In practical applications, depending on the need for polarization sensitivity or insensitivity, different photolithography plates can be used to lithographically create metal antennas of varying numbers and structures. For example, lithographically creating a linear dual-antenna structure can yield a high polarization ratio detector (achieving an ultra-high polarization ratio exceeding 600:1); lithographically creating an orthogonal four-antenna structure can yield a low polarization ratio detector (achieving an ultra-low polarization ratio of 1.2:1). Furthermore, the total length of the antenna is approximately half the target detection wavelength. For instance, when detecting a 6mm wavelength polarized electromagnetic wave, the total antenna length is approximately 3mm. S3. The fabricated device is cut and bonded to the test substrate using gold wire bonding, including the following processes: S31. The wafer is wire-cut to obtain a complete single device; S32. Using a wire bonding machine, bind the metal wire to the device and the base.

[0022] The prepared millimeter-wave detector is applied to the detection of highly sensitive weakly polarized electromagnetic signals, including the following steps: A1. Fix the millimeter-wave detector in the middle of the rotating bracket that can rotate 360 ​​degrees, and ensure that the rotation center of the millimeter-wave detector and the rotating bracket are on the same horizontal line. A2. Place the centers of the millimeter-wave signal source, chopper, and millimeter-wave detector on the same horizontal line; Connect the millimeter-wave detector to the preamplifier and lock-in amplifier; A3. Rotate the rotating bracket 360 degrees and read the polarization signal data output by the millimeter-wave detector from the lock-in amplifier.

[0023] Example 1 In this embodiment, InSb is selected as the semiconductor material. Using photolithography, etching, and thin film deposition processes, InSb is first fabricated into the desired cross-shaped structure. Then, titanium and gold are sequentially deposited at the corresponding positions using electron beam evaporation. Finally, through standard lift-off steps, a highly directionally selective and designable semiconductor plasmon millimeter-wave detector is fabricated. Specifically: (1) The epitaxially grown InSb wafer is etched into the designed cross-shaped structure using ultraviolet lithography, ensuring that no InSb remains in the etched area. The wafer structure includes a GaAs substrate, an Al substrate, and an Al substrate. 1-x In x Sb gradient layer, Al 0.15 In 0.85 Sb blocking layer and InSb active electron layer; (2) Using metal thin film growth equipment, including magnetron sputtering, electron beam evaporation, atomic layer deposition, etc., first deposit a titanium Ti layer, and then deposit the target structure and number of metal antennas; (3) Cut the prepared device and bond it to the test base using gold wire bonding.

[0024] In this embodiment, the InSb film thickness is 750 nm and the mobility is 30000 cm⁻¹. 2 V -1 s -1 The carrier concentration is 1.6e16 cm⁻¹ -3 The etching solution contains hydrofluoric acid: hydrogen peroxide: citric acid: deionized water in a ratio of 2:1:30:480. A single metal antenna is 2 mm long and has a thickness of 30 nm for Ti and 300 nm for Au. The number of antennas is 2 or 4 (as shown below). Figure 1 and Figure 2 (As shown).

[0025] In addition, during the cutting process, the edge should not exceed 3mm beyond the substrate, and the metal binding wire should be close to the tail of the antenna.

[0026] Polarization tests were performed on the fabricated semiconductor plasmonic millimeter-wave detector, and the results are as follows: Figure 3 and Figure 4 As shown: the polarization ratio of the detector with four antennas is approximately 1.2:1; the polarization ratio of the detector with two antennas exceeds 600:1.

[0027] Example 2 This embodiment is basically the same as Embodiment 1, except that the semiconductor material used in this embodiment is InGaAs, and its carrier concentration is 5.9e16cm. -3 The migration rate is 7500 cm. 2 V -1 s -1 The thickness is 3μm. In addition, the length of a single antenna of the detector is increased to 4mm, and the following are fabricated: Figure 5 and Figure 6 The millimeter-wave detector shown, and the corresponding polarization test results are as follows: Figure 7 and Figure 8As shown, similarly, the polarization ratio of the four-antenna detector is approximately 1.2:1; the ratio of the two-antenna detector exceeds 600:1.

[0028] In summary, this method fabricates a room-temperature millimeter-wave detector based on narrow-bandgap semiconductor SPP. This detector not only boasts a simple fabrication process and excellent performance, but also exhibits good millimeter-wave (wavelength 0.1-10 mm) polarization selectivity and excellent NEP (negative polarization efficiency), demonstrating room-temperature polarization selectivity for millimeter waves up to 10 nm. -14 WHz -0.5 This NEP, through a simple structural design, exhibits polarization selectivity of approximately 600:1 or 1.2:1 for 0° or 90° polarized light extinction ratios. Especially under high polarization selectivity, it can achieve continuous and resolvable optical signal detection and realize millimeter-wave full-angle detection. This detector shows important application prospects in multiple fields such as photoelectric detection, security detection, medical diagnosis, and space communication, and has significant promotional value and industrialization potential.

Claims

1. A millimeter wave probe, characterized by, The device includes a substrate on which a cross-shaped semiconductor structure is provided, and at the ends of the cross-shaped semiconductor structure a single-line dual-antenna structure or an orthogonal four-antenna structure is provided.

2. The millimeter wave probe of claim 1, wherein, A transition layer is provided between the substrate and the cross-shaped semiconductor structure, the transition layer including a gradient layer and a barrier layer.

3. The millimeter wave probe of claim 1, wherein, The cross-shaped semiconductor structure uses a narrow bandgap semiconductor material, including InSb, InGaAs, or HgTe.

4. A method for fabricating a millimeter-wave detector, used to fabricate the millimeter-wave detector as described in claim 1, characterized in that, Includes the following steps: S1. Etch the epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure, ensuring that there is no semiconductor residue in the etched area; S2. First, deposit a metal layer at the end of the cross-shaped semiconductor structure, and then deposit the target structure and number of metal antennas. S3. The prepared device is cut and bonded to the test base using gold wire bonding.

5. The method for fabricating a millimeter-wave detector according to claim 4, characterized in that, Specifically, step S1 involves using ultraviolet lithography to etch an epitaxially grown narrow bandgap semiconductor wafer into a cross-shaped structure. The narrow bandgap semiconductor wafer includes, from bottom to top, a substrate, a gradient layer, a barrier layer, and a narrow bandgap semiconductor active electron layer.

6. The method for fabricating a millimeter-wave detector according to claim 5, characterized in that, Step S1 includes the following process: S11. The epitaxially grown narrow bandgap semiconductor wafer is ultrasonically cleaned sequentially with acetone, alcohol and deionized water. S12. Photoresist is uniformly coated on a narrow bandgap semiconductor wafer, and patterning is performed using an ultraviolet lithography machine. The lithographic narrow bandgap semiconductor wafer is then placed in an etching solution for etching, retaining only the central cross-shaped pattern and not etching the barrier layer.

7. The method for fabricating a millimeter-wave detector according to claim 6, characterized in that, The etching solution in step S12 includes hydrofluoric acid, hydrogen peroxide, citric acid and deionized water, and is cleaned with deionized water after etching is completed.

8. The method for fabricating a millimeter-wave detector according to claim 6, characterized in that, Step S2 includes the following process: S21. The etched wafer from step S1 is coated with photoresist again and photolithography is performed. S22. For photolithographically etched wafers, deposit thin films of titanium and gold using a metal thin film evaporation equipment; S23. After the metal thin film is deposited, a stripping process is performed to obtain the target structure and number of metal antennas.

9. The method for fabricating a millimeter-wave detector according to claim 8, characterized in that, The metal antenna has a dipole-like structure, and its total length is half the target detection wavelength.

10. A millimeter-wave detection method, comprising using a millimeter-wave detector prepared by any one of the preparation methods described in claims 4 to 9 for millimeter-wave detection, characterized in that, Includes the following steps: A1. Fix the millimeter-wave detector in the middle of the rotating bracket that can rotate 360 ​​degrees, and ensure that the rotation center of the millimeter-wave detector and the rotating bracket are on the same horizontal line. A2. Place the centers of the millimeter-wave signal source, chopper, and millimeter-wave detector on the same horizontal line; Connect the millimeter-wave detector to the preamplifier and lock-in amplifier; A3. Rotate the rotating bracket 360 degrees and read the polarization signal data output by the millimeter-wave detector from the lock-in amplifier.

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