Ga2O3 baseline polarization solar blind detector and polarimeter
By preparing 2D Ga2O3 thin films and determining their crystal axis orientation, depositing interdigitated electrodes and fabricating twisted stacked structures, the problem of the difficulty in preparing Ga2O3 thin films was solved, realizing a high-performance Ga2O3 baseline polarization solar-blind detector and polarimeter, which promotes the development of polarization detection and imaging.
Patent Information
- Application Number
- CN202511433365.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-09
- Publication Date
- 2026-01-16
AI Technical Summary
Existing technologies make it difficult to prepare large-area, highly crystalline ultrathin Ga2O3 films, which limits the construction of heterojunctions/homogeneities and the development of high-performance integrated devices. At the same time, there is limited research on Ga2O3 polarization light detection and imaging.
2D Ga2O3 thin films were prepared by mechanical exfoliation. The c-axis and b-axis directions were determined by linearly polarized ultraviolet light. Interdigitated electrodes were deposited, and Ga2O3 baseline polarization solar-blind detectors were prepared by electron beam lithography and thermal evaporation. A polarimeter was fabricated by combining the polarization with a twisted stacked structure.
This study achieved highly polarization-sensitive solar-blind light response and high-resolution polarization imaging, and provided a method for fabricating high-performance Ga2O3 baseline polarization solar-blind detectors and polarimeters, thus promoting the development of polarization light detection and imaging.
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Figure CN121358014A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polarization detection and imaging technology, specifically relating to a Ga2O3 baseline polarization solar-blind detector and a polarimeter. Background Technology
[0002] Ultra-wide bandgap semiconductors have broad application prospects in fields such as solar-blind ultraviolet detection, fingerprint recognition, flame warning, and ozone / environmental monitoring, attracting widespread attention. Among these applications, solar-blind ultraviolet polarization detection and imaging can reflect more detailed optical information, which is crucial for the development of next-generation deep ultraviolet optoelectronic devices. Ga2O3, with its excellent optoelectronic properties, is considered an ideal material for applications in solar-blind ultraviolet optoelectronics and high-power electronics. In particular, Ga2O3 photodetectors are developing towards high performance and multifunctionality, primarily for monitoring the intensity, location, and polarization state of ultraviolet irradiation. Unfortunately, further progress in this area is mainly hindered by two problems. First, large-area, highly crystalline ultrathin Ga2O3 films are difficult to fabricate; existing reports only produce amorphous Ga2O3 thin layers, limiting the free construction of heterojunctions / homogeneities and even restricting the construction of high-performance integrated devices. Second, research on polarization detection and imaging of anisotropic Ga2O3 is relatively limited. Therefore, the development of polarized Ga2O3 solar-blind photodetectors with high device performance and reliable imaging capabilities is urgently needed. Summary of the Invention
[0003] The purpose of this invention is to address the aforementioned problems by providing a Ga2O3 baseline polarization solar-blind detector and polarimeter. It aims to fill the research gaps in Ga2O3 solar-blind photodetectors for polarization detection and imaging, and to promote the development of gallium oxide photodetectors in accurate polarization detection and high-resolution polarization imaging.
[0004] A Ga2O3 baseline polarization solar-blind detector is prepared by the following method:
[0005] 1) 2D Ga2O3 thin films were prepared by mechanical exfoliation and transferred onto a substrate;
[0006] 2) Irradiate the top of the 2D Ga2O3 film with linearly polarized ultraviolet light, rotate the platform to record the transmitted power, find the direction with the minimum transmitted power value as the polarization direction of the linearly polarized light, that is, the c-axis direction, and then the direction perpendicular to the c-axis direction is the b-axis direction.
[0007] 3) Interdigitated electrodes are deposited using electron beam lithography and thermal evaporation, with the interdigitated direction parallel to the b-axis;
[0008] The linearly polarized ultraviolet light described has λ=265 nm and P=1000 mW / cm. 2 .
[0009] The 2D Ga2O3 film is a 2D β-Ga2O3 film;
[0010] The substrate is PDMs or PDMs+Si / SiO2, and the electrode is a gold electrode.
[0011] Another object of the present invention is to provide a polarimeter based on a twisted stacked Ga2O3 baseline polarization solar-blind detector.
[0012] A polarimeter based on a twisted stacked Ga2O3 baseline polarization solar-blind detector consists of an amorphous Ga2O3 photodetector and two layers of Ga2O3 baseline polarization solar-blind detectors as described in any of claims 1-3, which are stacked sequentially from top to bottom on the polarimeter substrate.
[0013] The two layers of the Ga2O3 baseline polarization solar-blind detector are twisted and stacked, with their b-axis intersecting each other at an angle of 45°.
[0014] The amorphous Ga2O3 thin film is prepared by the following method:
[0015] 1) Melt liquid gallium by heating, drop it onto the surface of a substrate, and expose it to air under ultraviolet light.
[0016] 2) Soak in a pure ethanol solution at 45-55℃ for ultrasonic treatment;
[0017] 3) Electrodes are fabricated on amorphous gallium oxide thin films.
[0018] The substrate of the Ga2O3 baseline polarization solar-blind detector is PDMs; the polarizer substrate is Si / SiO2.
[0019] This invention provides a Ga2O3 baseline polarization solar-blind detector and a polarimeter. The Ga2O3 baseline polarization solar-blind detector mainly comprises: a Si / SiO2 or another PDMS substrate, a β-Ga2O3 thin film prepared by conventional mechanical lift-off method, and a bifid gold electrode prepared by electron beam lithography or thermal evaporation. The Si / SiO2 or another PDMS substrate serves as the bottom layer carrier, the β-Ga2O3 thin film serves as the middle photosensitive layer, and the bifid gold electrode absorbs photogenerated carriers from the β-Ga2O3 thin film on the top layer. By applying ultraviolet polarized light of a certain incident power density to irradiate the Ga2O3 baseline polarization solar-blind detector of this invention and measuring its transmission spectrum and other performance characterization data, it can be strongly demonstrated that this Ga2O3 baseline polarization solar-blind detector has a highly polarization-sensitive solar-blind light response. This greatly assists in the subsequent fabrication of a solar-blind polarization photodetector polarimeter using this Ga2O3 baseline polarization solar-blind detector. Attached Figure Description
[0020] Figure 1 This is the polarization-dependent transmission spectrum of a 2D β-Ga2O3 thin film;
[0021] Figure 2 Under certain incident light conditions, the dark current and polarization-dependent photocurrent of a Ga2O3 baseline polarization solar-blind detector have a high anisotropy ratio (approximately 2.8).
[0022] Figure 3 The graph shows the responsivity as a function of polarization angle under certain incident light conditions and a 4 V bias voltage. It demonstrates the good optical response of the device and its regular periodic variation with the polarization angle.
[0023] Figure 4 It is a polarimeter composed of three ultrathin Ga2O3 photodetectors stacked together. Among them, a is an amorphous Ga2O3 photodetector prepared by ultraviolet exposure of liquid gallium; b is a two-dimensional β-Ga2O3 photodetector with two layers stacked in a 45° twist, which can form a double symmetry broken.
[0024] Figure 5 It is linearly polarized light (power density 200 mW / cm²). 2 The photocurrents of channels I, II and III under irradiation with a wavelength of 265 nm and a bias of 2 V. Detailed Implementation
[0025] Example 1: A method for fabricating a Ga2O3 baseline polarization solar-blind detector
[0026] A method for fabricating a Ga2O3 baseline polarization solar-blind detector includes the following steps:
[0027] 1) Preparation of β-Ga2O3 thin film: β-Ga2O3 thin film with a thickness of about 6nm and a lateral dimension of not less than 5mm was prepared by conventional mechanical exfoliation method and grown on Si / SiO2 or another PDMS substrate.
[0028] 2) Determination of electrode deposition direction: First, it is necessary to clarify why this polarization-dependent absorption behavior can serve as a useful calibrator to determine the crystal axis orientation of a freshly prepared 2D β-Ga2O3 sample.
[0029] First, the electric vector (E) of incident light parallel to the c-axis of the 2D β-Ga₂O₃ thin film is defined as having an angle of 0°. (The rest of the text appears to be incomplete and requires further context.) Figure 1As can be seen, the optical transmittance changes significantly with increasing polarization angle, shifting from 4.50 eV < 0°, E / / c-axis > to 4.70 eV < 90°, E / / b-axis >, indicating that these 2D β-Ga₂O₃ films exhibit optical anisotropy. Therefore, this polarization-dependent absorption behavior can effectively determine the directions of the b and c axes.
[0030] a. First, a platform needs to be built to determine the orientation of the 2D β-Ga2O3 thin film along the b-axis and c-axis in the bc plane. This involves introducing a rotatable perforated platform and an ultraviolet power meter, which are used for loading / rotating the material and measuring the transmitted power, respectively.
[0031] b. Sample transfer: The 2D β-Ga2O3 thin film sample prepared by mechanical exfoliation is transferred to the hole on the platform for subsequent polarization measurement.
[0032] c. Begin measurement: Irradiate from the top with linearly polarized ultraviolet light (λ=265 nm, P=1000 mW / cm). 2 Then, by rotating the platform to record the transmitted power, the direction of minimum transmitted power is determined to be the polarization direction of linearly polarized light and the c-axis direction of the β-Ga₂O₃ thin film. The direction perpendicular to this is the b-axis direction of the 2D β-Ga₂O₃ thin film (see attached diagram). Figure 3 ).
[0033] d. The IV curves of β-Ga2O3 thin film samples with electrodes prepared along two different directions (b-axis and c-axis) were tested. The optoelectronic device prepared along the electrode preparation direction of the b-axis has better conductivity.
[0034] Gold electrode deposition: Using electron beam lithography and thermal evaporation, a pair of bifurcate gold electrodes with a thickness of 50 nm, a width of 50 μm, and a distance of 20 μm between each interdigitated gold electrode was deposited at the center of a 2D β-Ga₂O₃ sample. These devices were then vacuum annealed at 200 °C for 120 minutes. The deposition direction of this electrode pair can be along the b-axis.
[0035] Example 2 Characterization of polarization-sensitive light response characteristics of a 2D β Ga2O3 baseline polarization solar-blind detector
[0036] To demonstrate the polarization-sensitive optical response characteristics, a 265 nm laser was converted into linearly polarized light using a polarizer, with the incident power density set to 200 mW / cm². 2 .
[0037] As attached Figure 2As shown, the output current in the case of E / / c axis (the laser polarization direction parallel to the c-axis of 2D β-Ga2O3) is significantly greater than that in the case of E / / b axis, clearly revealing the polarization-related photoresponse behavior. The calculated anisotropy ratio, i.e., the ratio of the maximum photocurrent (E / / c axis) to the minimum photocurrent (E / / b axis), is approximately 2.8. As shown in the table below, this result is excellent in the field of ultraviolet polarization detection.
[0038]
[0039] Appendix Figure 3 The graph shows the responsivity as a function of the polarization angle (adjusted by rotating the half-wave plate). The optical response follows a sinusoidal periodic variation, confirming significant anisotropy in the responsivity. Note that the maximum responsivity occurs at 0° (E / / c axis), and the minimum occurs at 90° (E / / b axis), due to the lower transmittance (i.e., stronger absorption) along the E / / c axis. This polarization-dependent optical response behavior is stable and reproducible after 300 0 / 90° polarization switching tests.
[0040] The above results clearly demonstrate that the high anisotropy ratio Ga2O3 baseline polarization solar-blind detector (referred to as the 2D β-Ga2O3 photodetector) possesses a polarization-sensitive solar-blind light response. This provides a favorable basis for the subsequent feasibility of using this invention to fabricate further solar-blind polarization photodetector polarimeters.
[0041] Example 3: Fabrication of a polarimeter based on a twisted stacked Ga2O3 baseline polarization solar-blind detector
[0042] To detect the polarization direction and incident power of unknown linearly polarized light, a prototype polarimeter based on twisted stacked 2D β-Ga₂O₃ photodetectors was fabricated. Unlike traditional polarimeters with complex configurations including prisms, lenses, polarizers, waveplates, and filters, the polarimeter constructed here consists of only three ultrathin Ga₂O₃ photodetectors stacked on a UV-transparent PDMS substrate. Figure 4 .
[0043] Specifically, the preparation process involves using ultraviolet exposure of liquid gallium to prepare an amorphous Ga2O3 thin-film photodetector as the top layer.
[0044] The aforementioned amorphous Ga2O3 thin-film photodetector:
[0045] Liquid gallium was heated to 65 °C and placed on the upper surface of PDMS using a drop casting method. After exposure to ultraviolet light and ambient air for 15 minutes, a dense amorphous gallium oxide film was synthesized. The PDMS film was then immersed in a 50 °C pure ethanol solution and sonicated for 5 minutes to remove excess unoxidized liquid gallium. Finally, a gold electrode approximately 50 nm thick was fabricated on the amorphous gallium oxide film, forming a classic metal-semiconductor-metal photodetector. Figure 4 a).
[0046] This amorphous Ga2O3 top layer possesses isotropic optical and electrical properties and exhibits a unique linear photoresponse behavior to incident power density. This characteristic allows the top amorphous layer to function as a power meter, acting as channel I, by determining the photocurrent I. I The linear relationship between the photocurrent of channel I and the power density allows us to deduce the power value of the unknown incident light (this is the photoelectric performance of the Ga2O3 isotropic photodetector prepared by ultraviolet exposure of liquid metal). Next, two 2D β-Ga2O3 photodetectors are stacked as polarization sensors (channels II and III) under the top amorphous layer. Here, the two 2D β-Ga2O3 films are twisted at 45° during stacking; the specific twisting stacking method can be seen in the appendix. Figure 4 b.
[0047] In summary, the first layer is an amorphous Ga2O3 photodetector, while the second and third layers are 2D β-Ga2O3 photodetectors stacked at 45° to each other. PDMs (photodiodes permeable membranes) serve as insulating layers between these three Ga2O3 photodetectors, and also between the third photodetector and the Si / SiO2 substrate, to facilitate observation of the photoelectric behavior of each film. This structure exhibits a double-symmetry disruption: the first disruption stems from the intrinsic anisotropy of the β-Ga2O3 monoclinic crystal structure, while the second disruption is caused by the twisted stacking of the two β-Ga2O3 films.
[0048] Considering that the polarized photocurrent is within one period (0-180°, see appendix) Figure 5 The non-monotonic variation trend of the photocurrent means that a single measured current value may correspond to two different polarization angles. By employing a dual-symmetry broken device structure, the photocurrent values of channels II and III can be analyzed simultaneously (IL). II and I III This is used to definitively determine the polarization direction of linearly polarized light. (See attached image.) Figure 5As shown, the photocurrent of the top amorphous channel I exhibits a nearly constant value (i.e., non-polarization dependent) under different polarization angles, confirming the isotropic nature of the amorphous Ga2O3 layer. This means that the optical power information of the detected light can be obtained through this amorphous channel layer. In contrast, the photocurrents output from the twisted stacked β-Ga2O3 channels II and III show obvious polarization-dependent periodicity and a significant phase difference. Therefore, by simultaneously calculating the two photocurrent values of channels II and III, the polarization angle of the incident linearly polarized light can be accurately extracted. Combining the above studies on incident light power measurement performance and polarization angle measurement performance, it can be seen that by integrating three detectors based on different photosensitive material layers, a β-Ga2O3-based polarimeter prototype can conveniently provide information on the incident power and polarization direction of unknown linearly polarized light. This can facilitate further ultraviolet polarization imaging.
[0049] This invention provides a Ga2O3 baseline polarization solar-blind detector and its fabrication method. It employs a classic two-dimensional material fabrication method—mechanical exfoliation—to prepare a β-Ga2O3 thin film, and uses electron beam lithography and thermal evaporation to deposit electrodes. The operation is simple and easy to perform. Subsequent investigation of its polarization-sensitive light response performance revealed a high anisotropy ratio and excellent ultraviolet polarization detection performance. Using this invention, an ultraviolet solar-blind photodetector polarimeter was fabricated using a 45° double-layer twisted stack with an additional amorphous Ga2O3 top layer. The resulting detector exhibits superior polarization detection capability, allowing it to simultaneously detect the incident light power and, relying on the polarization characteristics of the twisted stacked Ga2O3 detector, obtain information such as the polarization angle of the incident light—achieving multiple benefits in one step. This solar-blind photodetector polarimeter can play a crucial role in the construction of polarization imaging systems.
Claims
1. A Ga2O3-based linear polarized solar blind photodetector, characterized in that: 1) a 2D Ga2O3 film is prepared by mechanical exfoliation and transferred to a substrate; 2) linear polarized ultraviolet light is irradiated from the top of the 2D Ga2O3 film, and the transmission power is recorded by rotating the platform to find the direction with the minimum transmission power, which is the polarization direction of the linear polarized light, i.e. the c-axis direction, and the direction perpendicular to the c-axis direction is the b-axis direction; 3) interdigital electrodes are deposited by electron beam lithography and thermal evaporation, and the interdigital direction is parallel to the b-axis. The 2D Ga2O3 film is a 2D β-Ga2O3 film. The substrate is PDMs or PDMs+Si / SiO2, and the electrode is a gold electrode. An amorphous Ga2O3 photodetector and two layers of any one of the Ga2O3-based linear polarized solar blind photodetectors according to claims 1-3 are stacked on a polarimeter substrate from top to bottom.
2. The Ga2O3-based linear polarized solar blind detector according to claim 1, wherein: The linearly polarized ultraviolet light has λ = 265 nm and P = 1000 mW / cm 2 .
3. The Ga2O3-based linear polarized solar blind detector according to claim 2, characterized in that: The two layers of the Ga2O3-based linear polarized solar blind photodetector are twisted and stacked, and the b-axes intersect with each other at an angle of 45°.
4. A Ga2O3-based linear polarized solar blind detector according to claim 1, 2 or 3, characterized in that: The amorphous Ga2O3 film is prepared by the following method:
5. A polarimeter based on a twisted stack Ga2O3 baseline polarizing solar blind detector characterized by: 1) Liquid gallium is heated and melted, and then dropped and cast on the surface of a substrate under ultraviolet irradiation and exposed to air; 6. The polarimeter based on the twisted stack Ga2O3 baseline polarizing solar blind detector according to claim 5, characterized in that: 2) Ultrasonic treatment in a 45-55℃ pure ethanol solution; 7. The polarimeter based on the twisted stack Ga2O3 baseline polarizing solar blind detector according to claim 6, characterized in that: 3) Electrodes are prepared on the amorphous gallium oxide film. The substrate of the Ga2O3-based linear polarized solar blind photodetector is PDMs, and the polarimeter substrate is Si / SiO2. 8. The polarimeter based on the twisted stack Ga2O3 baseline polarimetric solar blind detector according to claim 5, 6 or 7, characterized in that: