Single Sn-doped Ga2O3 microwire photodetector array and its fabrication method

Abstract

The application provides a single Sn-doped Ga2O3 microwire photoelectric detector array and a preparation method thereof. The photoelectric detector array comprises a substrate, and a Sn-doped Ga2O3 microwire is sequentially arranged on the substrate from bottom to top. A plurality of photoelectric detection units are sequentially and spacedly arranged on the substrate from left to right. The Sn-doped Ga2O3 microwire between adjacent photoelectric detection units is subjected to laser treatment. The application solves the crosstalk problem of photoelectric detector linear array imaging and realizes high-integration photoelectric detector array imaging.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, and in particular to a single Sn-doped Ga2O3 micron-wire photodetector array and its fabrication method. Background Technology

[0002] Solar radiation in the 200-280nm wavelength range is absorbed and scattered by the atmosphere and cannot reach the Earth's surface; this is known as the solar-blind band. Detectors operating in the solar-blind band can avoid interference from sunlight, exhibiting a high signal-to-noise ratio and a very low false alarm rate. Solar-blind ultraviolet imaging and position detection have wide applications in deep space exploration, missile early warning, and secure space communications.

[0003] Gallium oxide (GaO), as an ultra-wide bandgap semiconductor with a bandgap of 4.2-5.3 eV, exhibits a response spectrum covering most of the solar-blind band and possesses intrinsic solar-blind selectivity. This lays the foundation for solar-blind imaging technology using GaO devices. MSM structures have attracted widespread attention due to their simple fabrication, low cost, and ease of integration.

[0004] Although there are reports on gallium oxide photodetector arrays, under high integration conditions, devices will generate crosstalk, which will interfere with the imaging of the device. That is, when the measured unit is in the dark state and the surrounding units are illuminated, the measured unit exhibits a current close to that under illumination. Crosstalk is one of the important challenges faced by detectors under high integration architecture. At present, the main methods to solve crosstalk in gallium oxide photodetectors are as follows: (1) increasing the distance between the detection units, that is, increasing the blind zone. This method will significantly reduce the integration of the device and reduce the detection accuracy; (2) fabricating a dielectric isolation layer. This method is complex and costly; (3) reducing the width of the transit region. This method is similar to increasing the blind zone and will reduce the detection sensitivity of the detector. Summary of the Invention

[0005] This invention proposes a single Sn-doped Ga2O3 micron-wire photodetector array and its fabrication method. By using laser processing to treat the region between adjacent photodetector units, the region is made into a high-resistivity region, thereby effectively suppressing the crosstalk problem of the detector and realizing high-quality solar-blind imaging of the single Sn-doped Ga2O3 micron-wire photodetector array.

[0006] The technical solution of the present invention is implemented as follows: a single Sn-doped Ga2O3 micron-wire photodetector array, including a substrate, on which Sn-doped Ga2O3 micron-wires are disposed, and multiple photodetector units are disposed on the Sn-doped Ga2O3 micron-wires from left to right, and the Sn-doped Ga2O3 micron-wires between adjacent photodetector units are laser-processed.

[0007] Furthermore, the photoelectric detection unit consists of two adjacent metal electrodes, which are disposed on a Sn-doped Ga2O3 micrometer wire.

[0008] Furthermore, the metal electrode includes a Ti layer of 40–80 nanometers, and an Au layer of 50–100 nanometers is disposed on the upper side of the Ti layer.

[0009] Furthermore, the Sn-doped Ga2O3 microwires have a length of 2–6 mm and a diameter of 8–20 μm.

[0010] The fabrication method of a single Sn-doped Ga2O3 microwire photodetector array includes the following steps:

[0011] (1) Transfer Sn-doped Ga2O3 microwires onto a substrate, which is a sapphire substrate;

[0012] (2) Fix the Sn-doped Ga2O3 microwire from step (1) onto the substrate, such as by using silver paste to fix the two ends of the Sn-doped Ga2O3 microwire.

[0013] (3) Photoresist is spin-coated on the substrate in step (2), and multiple photodetector units are fabricated using laser direct writing lithography and magnetron sputtering. Specifically, this step involves: firstly, using laser direct writing lithography to fabricate a pattern of multiple photodetector units; then, using magnetron sputtering to fabricate a metal thin film, and using a lift-off process to remove it to obtain metal electrodes, with two adjacent metal electrodes forming a photodetector unit.

[0014] (4) The Sn-doped Ga2O3 micron-wires between adjacent photodetector units are processed by laser.

[0015] Furthermore, in step (3), the photolithography development time is 40-60 seconds.

[0016] Furthermore, in step (3), the argon flow rate used for magnetron sputtering is 10-30 sccm, and the DC power supply power is 50-80W.

[0017] Furthermore, in step (5), the laser used is a pulsed laser with a wavelength of 1064 nm.

[0018] Furthermore, in step (5), the laser frequency is 20 kHz, the average laser power is 2 W to 10 W, and the number of processing times is 30 to 100.

[0019] Furthermore, in step (1), the preparation method of Sn-doped Ga2O3 microwires is as follows:

[0020] 1) Depositing gold thin films on a substrate using magnetron sputtering technology;

[0021] 2) Anneal the substrate from step 1) to aggregate the gold film into particles;

[0022] 3) Sn-doped Ga2O3 microwires were prepared on the substrate of step 2) by chemical vapor deposition.

[0023] Furthermore, in step 2), the annealing temperature is 900℃.

[0024] Further, in step 3), a mixture of gallium oxide, tin oxide, and carbon powder in a mass ratio of 1:1:2 is placed on an alumina boat, and the substrate from step 2) is hung upside down on the alumina boat; then the alumina boat is loaded into a tube furnace, and during the growth process, argon and oxygen are injected into the tube while the tube is evacuated, the tube furnace is heated to 1160°C and held at that temperature for 1 hour; finally, the tube furnace is cooled to room temperature.

[0025] The beneficial effects of this invention are:

[0026] Under high integration conditions, photodetector units can generate crosstalk, which can interfere with the imaging of the device. This invention effectively suppresses the crosstalk problem of photodetectors by using pulsed laser processing in the area between adjacent photodetector units, thereby achieving high-quality solar-blind imaging of a single Sn-doped Ga2O3 microwire photodetector array. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a device structure containing 10 photoelectric detection units.

[0029] Figure 2 A schematic diagram of a device structure containing 20 photodetector units. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1As shown, a single Sn-doped Ga2O3 microwire photodetector array includes a substrate 4, on which Sn-doped Ga2O3 microwires 2 are sequentially arranged from bottom to top. Ten photodetector units are sequentially arranged on the substrate from left to right. The Sn-doped Ga2O3 microwires between adjacent photodetector units form region 3, which is processed using laser technology. By processing region 3 with laser, the photodetector array can achieve high-quality, high-resolution imaging.

[0033] Sn-doped Ga2O3 microwires have a length of 2–6 mm and a diameter of 8–20 μm. The substrate is an Al2O3 substrate with a thickness of 300–400 μm.

[0034] Preparation method of Sn-doped Ga2O3 microwires: Sapphire substrates were ultrasonically cleaned for 15 minutes in acetone, anhydrous ethanol and deionized water respectively, and then dried with high-purity nitrogen gas; a 500 nm gold film was deposited on the cleaned sapphire substrate using a magnetron sputtering system; then, the gold-plated sapphire substrate was placed in a high-temperature tube furnace and rapidly annealed at 900 °C. After annealing, the gold film on the sapphire aggregated into particles.

[0035] A mixture of gallium oxide, tin oxide, and carbon powder (mass ratio 1:1:2) was placed on an alumina boat, and a sapphire / gold particle substrate was hung upside down on the alumina boat. The alumina boat was then loaded into a tube furnace. During the growth process, argon (200 sccm) and oxygen (5 sccm) were injected into the tube, and a vacuum was simultaneously applied to the tube using a mechanical pump (pumping speed = 4 L / s). The tube furnace was heated to 1160°C and held at that temperature for 1 hour. Finally, the tube furnace was cooled to room temperature.

[0036] The fabrication method of a single Sn-doped Ga2O3 microwire photodetector array includes the following steps:

[0037] (1) Clean the substrate with acetone, anhydrous ethanol and ultrapure water for 10 minutes each, and then dry it with high-purity nitrogen.

[0038] (2) Use tweezers to transfer the Sn-doped Ga2O3 microwire to the substrate, fix the two ends of the Sn-doped Ga2O3 microwire with silver paste, and heat to 150°C to solidify the silver paste;

[0039] (3) The laser direct writing lithography steps are as follows: First, draw the pattern to be used, with an electrode spacing of 150 micrometers. Then spin-coat the photoresist and heat it at 115℃ for 2 minutes. Then place it in the laser direct writing lithography machine for exposure. After exposure, take it out and develop it for 45 seconds to obtain the desired pattern.

[0040] Titanium was sputtered using magnetron sputtering technology. The magnetron sputtering steps are as follows: The developed substrate is placed in the sputtering chamber. Before sputtering, the vacuum in the growth chamber is evacuated to below 2.0 × 10⁻⁶ using a molecular pump. -4 Pa; Argon gas was introduced during the growth process, and the gas flow rate was maintained at 15 sccm. The power of the entire sputtering process was 60W, and the growth pressure was 2Pa. Titanium was sputtered first for 1 minute, and the sputtering thickness was about 50 nanometers. Gold was then sputtered for 2 minutes, and the sputtering thickness was about 90 nanometers.

[0041] The desired electrode pattern is obtained by using a lift-off process, and two adjacent metal electrodes form a photoelectric detection unit.

[0042] (4) Use a pulsed laser with a wavelength of 1064nm to process the region 3 between adjacent photoelectric detection units. The laser frequency is set to 20kHz, the average power is adjusted to 4W, and the number of processing times is 40. It is difficult to focus the laser directly onto the micrometer line. Therefore, the laser movement trajectory is set as a line segment perpendicular to the micrometer line. The laser moving from one end of the line segment to the other end is considered as one processing time.

[0043] Example 2

[0044] This embodiment is basically the same as Embodiment 1, except for the number of photodetector units and the method of preparing a single Sn-doped Ga2O3 micron-wire photodetector array.

[0045] like Figure 2 As shown, a single Sn-doped Ga2O3 micron-wire photodetector array includes a substrate 4, on which Sn-doped Ga2O3 micron-wires 2 are arranged sequentially from bottom to top, and 20 photodetector units are arranged sequentially from left to right. The Sn-doped Ga2O3 micron-wires between adjacent photodetector units form region 3, which is processed by laser.

[0046] The fabrication method of a single Sn-doped Ga2O3 microwire photodetector array includes the following steps:

[0047] (1) Clean the substrate with acetone, anhydrous ethanol and ultrapure water for 10 minutes each, and then dry it with high-purity nitrogen.

[0048] (2) Use tweezers to transfer the Sn-doped Ga2O3 microwire onto the substrate, fix the two ends of the wire with silver paste, and heat to 150°C to solidify the silver paste;

[0049] (3) The laser direct writing lithography steps are as follows: First, draw the pattern to be used, with an electrode spacing of 300 micrometers. Then spin-coat the photoresist and heat it at 115°C for 2 minutes. Then place it in the laser direct writing lithography machine for exposure. After exposure, take it out and develop it for 45 seconds to obtain the desired pattern.

[0050] Titanium was sputtered using magnetron sputtering technology. The magnetron sputtering steps are as follows: The developed substrate is placed in the sputtering chamber. Before sputtering, the vacuum in the growth chamber is evacuated to below 2.0 × 10⁻⁶ using a molecular pump. -4 Pa; Argon gas was introduced during the growth process, and the gas flow rate was maintained at 10 sccm. The power of the entire sputtering process was 70W, and the growth pressure was 2.5Pa. Titanium was sputtered first for 1 minute, and the sputtering thickness was about 60 nanometers. Gold was then sputtered for 2 minutes, and the sputtering thickness was about 100 nanometers.

[0051] The desired electrode pattern is obtained by using a lift-off process, and two adjacent metal electrodes are combined to form a photoelectric detection unit.

[0052] (4) Use a pulsed laser with a wavelength of 1064nm to process the region 3 between adjacent photoelectric detection units. The laser frequency is set to 20kHz, the average laser power is set to 6W, and the number of processing times is 30.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single Sn-doped Ga2O3 microwire photodetector array, comprising a substrate, characterized in that: Sn-doped Ga2O3 microwires are disposed on the substrate. Multiple photodetector units are arranged on the Sn-doped Ga2O3 microwires from left to right. The Sn-doped Ga2O3 microwires between adjacent photodetector units are laser-processed to make the Sn-doped Ga2O3 microwires between adjacent photodetector units a high-resistivity region.

2. The single Sn-doped Ga2O3 microwire photodetector array according to claim 1, characterized in that: The photoelectric detection unit consists of two adjacent metal electrodes, which are disposed on a Sn-doped Ga2O3 micron-wire.

3. The single Sn-doped Ga2O3 microwire photodetector array according to claim 2, characterized in that: The metal electrode includes a 40-80 nm Ti layer, and an Au layer of 50-100 nm is disposed on the upper side of the Ti layer.

4. The single Sn-doped Ga2O3 microwire photodetector array according to any one of claims 1-3, characterized in that: Sn-doped Ga2O3 microwires have a length of 2–6 mm and a diameter of 8–20 µm.

5. A method for fabricating a single Sn-doped Ga2O3 micron-wire photodetector array, characterized in that, Includes the following steps: (1) Transfer Sn-doped Ga2O3 microwires onto a substrate, which is a sapphire substrate; (2) Fix the Sn-doped Ga2O3 microwire from step (1) onto the substrate, such as by using silver paste to fix both sides of the Sn-doped Ga2O3 microwire; (3) Photoresist is spin-coated on the substrate in step (2), and multiple photoelectric detection units are fabricated using laser direct writing lithography and magnetron sputtering techniques; (4) The Sn-doped Ga2O3 micrometer line between adjacent photodetector units is processed by laser; the laser used is a pulsed laser with a wavelength of 1064 nm; the laser frequency is 20 kHz, the average laser power is 2 W to 10 W, and the number of processing times is 30 to 100 times; wherein, the laser movement trajectory is set as a line segment perpendicular to the micrometer line, and the laser moving from one end of the line segment to the other end is considered as one processing time.

6. The method for fabricating a single Sn-doped Ga2O3 microwire photodetector array according to claim 5, characterized in that, In step (3), the photolithography development time is 40~60 seconds.

7. The method for fabricating a single Sn-doped Ga2O3 microwire photodetector array according to claim 5 or 6, characterized in that, In step (3), the argon flow rate used for magnetron sputtering is 10~30 sccm, and the DC power supply power is 50~80 W.

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