A GaN-based ITO transparent electrode ultraviolet photoelectric sensor and a preparation method thereof

Abstract

The application discloses a GaN-based ITO transparent electrode ultraviolet photoelectric sensor, which comprises a substrate, an n-type GaN epitaxial layer, an ITO transparent electrode layer, a metal lead-out layer and a passivation layer; wherein the substrate, the n-type GaN epitaxial layer, the ITO transparent electrode layer and the passivation layer are stacked from bottom to top, the metal lead-out layer is arranged at the end of the ITO transparent electrode layer to lead out a signal, graphene quantum dots (GQDs) are doped in the ITO transparent electrode layer, and an ultrathin h-BN interface buffer layer can be additionally arranged on the surface of the n-type GaN epitaxial layer. The application further discloses a preparation method of the sensor. The ITO transparent interdigital electrode, the metal lead-out layer and the passivation layer are used in cooperation, and the GQDs doping and the h-BN interface buffer are used as auxiliary means, so that the comprehensive performance of the device is significantly improved among high responsivity, low dark current and fast response, and the ultraviolet detection sensitivity, the ultraviolet / visible light suppression ratio and the long-term stability are substantially improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, specifically relating to a GaN-based ITO transparent electrode ultraviolet photoelectric sensor and its fabrication method. Background Technology

[0002] Ultraviolet photoelectric detection technology is widely used in fields such as power detection, fire safety, aerospace, environmental monitoring, and smart wearables, and is a core technology of modern intelligent sensing. GaN material, with its advantages such as a wide bandgap of 3.4 eV, high temperature resistance, and high carrier mobility, has become the preferred semiconductor material for fabricating high-performance ultraviolet detectors.

[0003] Traditional GaN-based ultraviolet detectors employ Ti / Au metal electrodes, which suffer from high light absorption loss and form Schottky contacts with n-GaN, resulting in low carrier transport efficiency and directly limiting device responsivity and response speed. While using ITO transparent electrodes can reduce light absorption, the ITO prepared by conventional electron beam evaporation processes still forms a Schottky contact with n-GaN, leading to high contact resistance. High-temperature annealing optimization processes can easily damage GaN materials and have poor compatibility with integration processes. Existing ITO / GaN ultraviolet detectors also suffer from high dark current and insufficient long-term stability, making them unsuitable for high-end applications.

[0004] Chinese patent CN114204054A discloses a GaN-based MSM structure ultraviolet photodetector. Although it uses ITO as a transparent electrode to reduce light absorption loss, it still employs conventional deposition processes to fabricate ITO, resulting in low interfacial carrier transport efficiency and significant shortcomings in device photoresponsivity and operational stability. Chinese patent CN112366250B discloses a GaN-based ultraviolet detector and its fabrication method. While it improves the initial photoresponse performance to some extent in the field of ultraviolet detection by optimizing the epitaxial structure and electrode fabrication process, it suffers from defects such as significantly increased dark current, continuous decay of photoresponsivity, electrode interface bonding failure, and lack of structural stability during long-term high-temperature and high-humidity cycling. This demonstrates the common shortcomings of existing technologies in synergistically improving photoelectric performance and long-term reliability. Summary of the Invention

[0005] The purpose of this invention is to provide a GaN-based ITO transparent electrode ultraviolet photoelectric sensor and its fabrication method.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a GaN-based ITO transparent electrode ultraviolet photoelectric sensor, comprising a substrate, an n-type GaN epitaxial layer, an ITO transparent electrode layer, a metal lead-out layer, and a passivation layer, wherein the substrate, the n-type GaN epitaxial layer, the ITO transparent electrode layer, and the passivation layer are arranged sequentially from top to bottom, and the metal lead-out layer is disposed at the end of the ITO transparent electrode layer.

[0008] In this invention, the ITO transparent electrode layer, the metal lead-out layer, and the passivation layer form a significant synergistic effect: the ITO transparent interdigitated electrode ensures high ultraviolet transmittance while forming a low-resistance ohmic contact with n-GaN, maximizing the generation and injection efficiency of photogenerated carriers; the metal lead-out layer provides a reliable electrical connection with extremely low contact resistance at the end of the ITO electrode, effectively collecting and transmitting carriers to external circuits, avoiding signal loss due to poor electrode lead-out; the passivation layer covers the device surface, suppressing surface leakage current, reducing dark current, and preventing oxidation and degradation of the ITO and GaN layers, thereby stabilizing the interface states. The combined effect of these three elements enables a synergistic improvement in high responsivity, low dark current, and fast response: the photoelectric conversion efficiency of the ITO layer is efficiently output by the Ti / Au layer, while the interface protection of the passivation layer, in turn, amplifies the low-noise advantage of the ITO / metal electrode, ultimately achieving superior overall detection performance compared to any single element or combination of elements.

[0009] Preferably, the substrate thickness is 200-430 μm, the n-type GaN epitaxial layer thickness is 2-3 μm, the ITO transparent electrode layer thickness is 80-110 nm, the passivation layer thickness is 90-150 nm, and the total thickness of the metal lead-out layer is 60-130 nm.

[0010] Preferably, the substrate material is sapphire.

[0011] Preferably, Si is incorporated into the n-type GaN epitaxial layer as an n-type dopant, and the concentration of n-type carriers introduced by Si doping is 1 × 10⁻⁶. 18 cm -3 ~3×10 18 cm -3

[0012] Preferably, the electrode pattern of the ITO transparent electrode layer is an MSM interdigitated structure, with an electrode width of 1-2 μm, an electrode spacing of 2-4 μm, and an electrode length of 50-100 μm.

[0013] Preferably, the metal lead-out layer comprises Ti / Au or Ti / Cr / Au.

[0014] Preferably, the ITO transparent electrode layer is doped with GQDs at a concentration of 0-0.5%.

[0015] Preferably, the passivation layer comprises SiO2 or a composite of SiO2 and Si3N4.

[0016] Preferably, it further includes an h-BN interface buffer layer, wherein the h-BN interface buffer is disposed on the surface of the n-type GaN epitaxial layer.

[0017] Secondly, the present invention provides a method for fabricating a GaN-based ITO transparent electrode ultraviolet photoelectric sensor, comprising the following steps:

[0018] S1. Clean the substrate and dry it for later use;

[0019] S2. An n-type GaN epitaxial layer is grown on the substrate to obtain an n-GaN photosensitive layer;

[0020] S3. Fabrication of ITO transparent interdigitated electrodes:

[0021] (1) Using radio frequency magnetron sputtering equipment, ITO (In2O3:SnO2≈90:10) target material with a purity ≥99.99% is used to deposit ITO thin film on the surface of n-type GaN epitaxial layer at room temperature; the process parameters are radio frequency power 25~30W, working vacuum degree 1.33Pa, Ar / O2 volume flow ratio 95:5, and deposition time 55~75min; optionally, GQDs vapor is introduced into the sputtering atmosphere to achieve GQDs doping (mass fraction 0~0.5%).

[0022] (2) MSM interdigitated electrode pattern is prepared by photolithography: spin-coating photoresist on the surface of ITO thin film, pre-baking, exposure using interdigitated mask, development, hardening to form interdigitated pattern photoresist mask; then wet etching (ITO etching solution, such as HCl:HNO3 or FeCl3-based etching solution, room temperature, etching until n-GaN surface is exposed) removes excess ITO not protected by photoresist, and transparent interdigitated electrode structure is formed after photoresist removal.

[0023] (3) Annealing in a nitrogen (N2) atmosphere: annealing temperature 480-500℃, holding for 60-90min, so that ITO and n-GaN (or ITO / h-BN / n-GaN) form a high-quality ohmic contact.

[0024] S4. A double metal layer is evaporated and deposited at the electrode tip as a lead-out electrode;

[0025] S5. Deposit passivation layer: A passivation layer is deposited on the active region and electrode surface of the device using plasma-enhanced chemical vapor deposition (PECVD). This can be a single layer of SiO2, or a composite layer of SiO2 followed by Si3N4. The ends of the metal lead-out layer are retained as bonding pads to complete the sensor fabrication.

[0026] Preferably, in step S3, the sputtering parameters are set as follows: RF power 25 W-30 W, working vacuum 1.33 Pa, Ar / O2 volumetric flow rate ratio 95:5, and deposition time 55 min-75 min.

[0027] Preferably, in step S2, the growth temperature is 1000-1200℃.

[0028] Preferably, the process further includes growing an h-BN interface buffer layer on the n-GaN surface at a growth temperature of 500-600℃ and a nitrogen source flow rate of 5-15 sccm to protect the interface integrity.

[0029] Preferably, in step S3, the annealing temperature is 480-500℃ and the holding time is 60-90 minutes.

[0030] Preferably, in step S3, the MSM interdigitated electrode pattern is defined using photolithography, and excess ITO is removed by wet etching.

[0031] Preferably, in step S5, a passivation layer is deposited using a PECVD process.

[0032] The beneficial effects of this invention are as follows:

[0033] Compared with existing technologies, this invention uses ITO transparent interdigitated electrodes to replace traditional opaque metal electrodes, completely eliminating the absorption loss of ultraviolet incident light and significantly improving the photoelectric responsivity of the device. The metal lead-out layer forms a reliable electrical connection with extremely low contact resistance at the end of the ITO electrode, ensuring efficient collection and transmission of photogenerated carriers and avoiding signal loss. The passivation layer covers the device surface, effectively suppressing surface leakage current, reducing dark current, and preventing oxidation and degradation of the ITO and GaN layers, thereby stabilizing the interface states. The synergistic effect of the ITO transparent interdigitated electrodes, the metal lead-out layer, and the passivation layer enables the device to achieve a significant improvement in overall performance between high responsivity, low dark current, and fast response, with substantial improvements in ultraviolet detection sensitivity and signal-to-noise ratio.

[0034] The fabrication process of this invention has the following advantages: 1. It uses radio frequency magnetron sputtering to deposit ITO transparent interdigitated electrodes, enabling ITO and n-GaN to directly form high-quality ohmic contacts. Compared with electron beam evaporation, the interface resistance is significantly reduced, and the carrier transport efficiency is higher; 2. The entire fabrication process is compatible with standard semiconductor processes, requiring no complex equipment or special steps. The light-emitting / detector unit can be integrated on a sapphire substrate in a single step, resulting in good process repeatability and high yield; 3. The passivation layer uses deposition technology, seamlessly integrating with the fabrication processes of the ITO electrodes and Ti / Au lead-out layers without adding additional photolithography steps. This invention features a simple process, controllable cost, and suitability for mass production. The resulting device combines the advantages of high responsivity, low dark current, and fast response speed. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments 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.

[0036] Figure 1 This is a schematic cross-sectional view of the GaN-based ITO transparent electrode ultraviolet photoelectric sensor of the present invention, wherein the left side view corresponds to Examples 1-3 and the right side view corresponds to Examples 4-5.

[0037] Figure 2 This is a schematic diagram comparing the responsivity and photocurrent ratio of different embodiments and comparative devices.

[0038] Figure 3 This is a schematic diagram comparing the dark current (logarithmic scale) and long-term performance degradation rate of different embodiments and comparative devices.

[0039] Figure label: Figure 1 In the diagram, 1. Substrate, 2. n-type GaN epitaxial layer, 3. h-BN interface buffer layer, 4. ITO transparent electrode layer, 5. Metal lead-out layer, and 6. Passivation layer. Detailed Implementation

[0040] This invention provides a GaN-based ITO transparent electrode ultraviolet photoelectric sensor, comprising a substrate, an n-type GaN epitaxial layer, an ITO transparent electrode layer, a metal lead-out layer, and a passivation layer; the substrate, n-type GaN epitaxial layer, ITO transparent electrode layer, and passivation layer are stacked from bottom to top, and the metal lead-out layer is disposed at the end of the ITO transparent electrode layer. The substrate material is preferably sapphire; the metal lead-out layer comprises Ti / Au or Ti / Cr / Au; the mass fraction of GQDs doped in the ITO transparent electrode layer is 0–0.5%; the passivation layer comprises a SiO2 monolayer or a composite of SiO2 and Si3N4.

[0041] In some embodiments, the sensor further includes an h-BN interface buffer layer disposed on the surface of the n-type GaN epitaxial layer and below the ITO transparent electrode layer, with a thickness of 1 to 2 nm.

[0042] In some embodiments, the substrate thickness is 200–430 μm; the n-type GaN epitaxial layer thickness is 2–3 μm; and the carrier concentration introduced by Si doping is 1 × 10⁻⁶. 18 ~3×10 18 cm -3The ITO transparent electrode layer has a thickness of 80–110 nm, and the electrode pattern is an MSM interdigitated structure. The electrode width is 1–2 μm, the spacing is 2–4 μm, and the length is 50–100 μm. The passivation layer has a thickness of 90–150 nm. The total thickness of the metal lead-out layer is 60–130 nm (Ti / Au: Ti 15–25 nm, Au 95–105 nm; Ti / Cr / Au: Ti 10–20 nm, Cr 3–5 nm, Au 50–100 nm).

[0043] The preparation method of this invention includes steps S1 to S5, and the specific process parameters and positions are as described in the "Summary of the Invention" section above. The invention will be further illustrated below with reference to embodiments and comparative examples.

[0044] Example 1

[0045] This embodiment provides a GaN-based ITO transparent electrode ultraviolet photoelectric sensor, comprising a sapphire substrate, an n-type GaN epitaxial layer, an ITO transparent electrode layer, a Ti / Au metal lead-out layer, and a SiO2 passivation layer. The substrate thickness is 430 μm; the n-type GaN epitaxial layer thickness is 3 μm; and the Si doping carrier concentration is 2 × 10⁻⁶. 18 cm -3 The ITO transparent electrode layer is 110 nm thick; the electrode pattern is an MSM interdigitated structure with an electrode width of 2 μm, a spacing of 4 μm, and a length of 100 μm; the metal lead-out layer is a 20 nm Ti layer and a 100 nm Au layer; the SiO2 passivation layer is 150 nm thick.

[0046] Preparation method: S1. Sapphire substrate was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water for 10 min, dried with nitrogen, and then dried in an oven at 80℃ for 30 min; S2. n-type GaN epitaxial layer was grown by MOCVD at 1100℃ with Si doping carrier concentration of 2×10¹⁸ cm⁻³ and a thickness of 3 μm; S3. ITO purity was sputtered by RF magnetron sputtering at room temperature, power 30W, cavity pressure 1.33 Pa, Ar / O₂=95:5 for 75 min to obtain a 110 nm ITO thin film; photolithography and wet etching were used to form interdigitated electrodes; N₂ annealing was performed at 500℃ for 90 min to form ITO / n-GaN ohmic contacts; S4. Ti (20 nm) / Au (100 nm) lead-out electrodes were formed by electron beam evaporation at the electrode ends; S5. A 150 nm SiO₂ passivation layer was deposited by PECVD, retaining the pads, to complete the preparation.

[0047] Example 2

[0048] This embodiment provides a high-sensitivity GaN-based composite transparent electrode ultraviolet photoelectric sensor, comprising a sapphire substrate, an n-type GaN epitaxial layer, an ultrathin h-BN interface buffer layer, a GQDs-doped ITO transparent electrode layer, a Ti / Cr / Au metal lead-out layer, and a SiO2 / Si3N4 composite passivation layer. The substrate is 430 μm thick; the n-type GaN epitaxial layer is 3 μm thick; and the Si doping carrier concentration is 2 × 10⁻⁶. 18 cm -3 The h-BN buffer layer is 2nm, grown on the n-GaN surface; the GQDs-doped ITO film is 110nm, with a GQDs mass fraction of 0.5%; the electrode MSM interdigitated fingers are 2μm wide, 4μm apart, and 100μm long; the Ti / Cr / Au structure consists of Ti 20nm, Cr 5nm, and Au 100nm; the composite passivation layer is SiO2 80nm + Si3N 470nm (total 150nm).

[0049] Preparation method: S1. Same as in Example 1; S2. Same as in Example 1 to obtain an n-GaN sensitive layer; S3. MBE to grow a 2nm h-BN buffer layer on the n-GaN surface (550℃, nitrogen source 10sccm); S4. RF magnetron sputtering to introduce GQDs vapor (mass fraction 0.5%), the rest is the same as in Example 1 to obtain 110nm GQDs-ITO; photolithography + wet etching to form interdigitated fingers; N2 annealing at 500℃ for 90min to form ITO / h-BN / n-GaN ohmic contacts; S5. Electron beam evaporation of Ti (20nm) / Cr (5nm) / Au (100nm) at the electrode end to form the lead-out electrode; S6. PECVD to sequentially deposit an 80nm SiO2 and a 70nm Si3N4 composite passivation layer to complete the preparation.

[0050] Example 3

[0051] This embodiment provides a miniaturized, high-sensitivity GaN-based composite transparent electrode ultraviolet photoelectric sensor, comprising a sapphire substrate, an n-type GaN epitaxial layer, an ultrathin h-BN interface buffer layer, a GQDs-doped ITO transparent electrode layer, a Ti / Cr / Au metal lead-out layer, and a SiO2 / Si3N4 composite passivation layer. The substrate is 200 μm thick; the n-type GaN epitaxial layer is 2 μm thick; and the Si doping carrier concentration is 2 × 10⁻⁶. 18 cm -3 h-BN buffer layer 1nm; GQDs-doped ITO film 80nm, GQDs mass fraction 0.5%; electrode MSM interdigitated fingers, width 1μm, spacing 2μm, length 50μm; Ti / Cr / Au: Ti 10nm, Cr 3nm, Au 50nm; composite passivation layer SiO2 50nm + Si3N 440nm (total 90nm).

[0052] Fabrication method: S1. Substrate cleaning for 8 min, drying at 80℃ for 20 min; S2. MOCVD growth of n-GaN (1100 ℃) to 2 μm; S3. MBE growth of 1 nm h-BN (550℃, nitrogen source 8 sccm); S4. RF magnetron sputtering of GQDs-ITO (power 25W, cavity pressure 1.33Pa, Ar / O2=95:5, sputtering for 55 min) to obtain 80 nm; electron beam lithography + dry etching to form micro interdigitated fingers; N2 annealing at 480℃ for 60 min; S5. Electron beam evaporation of Ti (10 nm) / Cr (3 nm) / Au (50 nm); S6. PECVD deposition of 50 nm SiO2 + 40 nm Si3N4 to complete the fabrication of miniaturized sensor.

[0053] Example 4 (Study on the Influence of Sputtering Parameters)

[0054] In this embodiment, referring to the sensor structure and fabrication process of Example 2, only the single process parameter of RF magnetron sputtering was changed, while the other parameters remained the same as the optimal conditions of Example 2 (30W, 1.33Pa, Ar / O2=95:5, 75min). The following treatment groups were set up to examine the effect of each parameter on the device performance:

[0055]

[0056] Comparative Example

[0057] Comparative Example 1: Essentially the same as Example 2, except that an opaque Ni / Au metal electrode was used instead of a transparent ITO electrode. The difference in preparation method was that Ni (20 nm) / Au (100 nm) interdigitated electrodes were sequentially deposited on the n-GaN surface using electron beam evaporation (vacuum degree ≤ 5 × 10⁻⁶). -4 Pa, deposition rate 0.1-0.5 nm / s, substrate not heated), and GQDs doping and h-BN buffer layer omitted; the rest is the same as in Example 2.

[0058] Comparative Example 2: Basically the same as Example 2, except that the metal lead-out layer and passivation layer are omitted (i.e., only ITO interdigitated electrodes are prepared, and the ITO ends are used directly as contact points). The rest is the same as Example 2.

[0059] Comparative Example 3: Basically the same as Example 2, except that the metal lead-out layer is omitted (the passivation layer is retained, but there is no Ti / Cr / Au lead-out at the ITO interdigital ends). The rest is the same as Example 2.

[0060] Comparative Example 4: Basically the same as Example 2, except that the passivation layer is omitted (the metal lead-out layer is retained). The rest is the same as Example 2.

[0061] Comparative Example 5: Essentially the same as Example 2, except that electron beam evaporation of ITO was used instead of radio frequency magnetron sputtering of ITO. The difference in preparation method is that electron beam evaporation was used at room temperature and a vacuum degree ≤5×10⁻⁶. -4 A 110 nm ITO film was deposited under Pa and deposition rate of 0.5–2 nm / s conditions. The remaining annealing, photolithography, metal extraction and passivation steps were the same as in Example 2.

[0062] Comparative Example 6: Basically the same as Example 2, except that GQDs are not incorporated into the ITO transparent electrode layer (GQDs mass fraction is 0%). The rest is the same as Example 2.

[0063] Performance testing

[0064] 1. Dark Current and Photocurrent Testing: In a shielded anechoic chamber, a semiconductor parameter analyzer (such as Keithley 4200A or 2636B) with a probe station is used to apply a -5V to +5V bias scan to the device; first, the dark-state IV curve is recorded under no-light conditions to obtain the dark current I_dark; then, a UV-LED with a center wavelength of 365nm (incident light power density of 1mW / cm²) is used to measure the dark current. 2 Irradiate the active region uniformly, record the bright-state IV curve to obtain the photocurrent I_ph; calculate the photo-dark current ratio I_ph / I_dark.

[0065] 2. Spectral response test: The incident light was scanned in the range of 200-450nm with a step size of 1-5nm using a monochromator. The incident light power P_in(λ) at each wavelength was calibrated using a calibrated UV-enhanced detector. The photocurrent I_ph(λ) of the recording device was recorded. The spectral responsivity was calculated according to R(λ)=I_ph(λ) / P_in(λ). The UV / visible suppression ratio was defined as the ratio of peak responsivity to responsivity in the visible region (≥400nm).

[0066] 3. Time response test: Irradiate the device with a 365nm pulsed light source (such as a UV-LED or pulsed laser modulated by a function generator, with a modulation frequency of 1kHz and a duty cycle of 50%), biased at 5V, and record the rise / fall transient of the photocurrent using a broadband oscilloscope; the 10% to 90% amplitude range is defined as the rise time t_r and the fall time t_f, respectively.

[0067] 4. Repeatability and stability testing: Take multiple devices from the same batch and perform the above tests 1 to 3. Calculate the mean and standard deviation of each performance parameter to evaluate repeatability. In addition, conduct long-term reliability testing on the devices—continuously operate under constant temperature and humidity conditions of 85℃ / 85%RH, or undergo 100 thermal cycles of -40℃ to 125℃. Periodically test the responsivity and dark current, calculate the performance degradation rate = (initial value - test value) / initial value × 100%, and observe the long-term degradation.

[0068] Test Results, Data Analysis and Conclusions

[0069]

[0070] The test data for the above embodiments and comparative examples are shown in the table below:

[0071] Based on the table above, the following conclusions can be drawn:

[0072] (1) There is a clear optimization window for sputtering parameters: Example 2 (30W, 1.33Pa, Ar / O2=95:5, 75min) is the best; the performance of treatment groups 4-1 (low power), 4-2 (high power), 4-3 / 4-4 (vacuum degree deviation), 4-5 (pure Ar lack of O2 leads to oxygen deficiency of ITO, reduced light transmittance and conductivity), 4-7 (short time, thin film), and 4-8 (long time, thick film) are all inferior to Example 2, which confirms the rationality of the parameter range defined in the claims and specification.

[0073] (2) The three-layer synergistic effect is significant: Comparative Example 2 (omitting the metal lead-out layer and passivation layer) has the worst performance, with the largest dark current and attenuation rate and the lowest responsivity; Comparative Example 3 (omitting the metal lead-out layer) and Comparative Example 4 (omitting the passivation layer) have performances that are inferior to Example 2, indicating that the metal lead-out layer and passivation layer are indispensable to each other and together amplify the advantages of the ITO transparent electrode.

[0074] (3) ITO transparent electrodes are superior to opaque metal electrodes: Comparative Example 1 (Ni / Au replaces ITO) has significantly lower photocurrent, responsivity and suppression ratio than Example 2 because the electrode absorbs ultraviolet light and easily forms Schottky contacts.

[0075] (4) Radio frequency magnetron sputtering is superior to electron beam evaporation: Comparative Example 5 (electron beam evaporation ITO) has poor contact quality, increased dark current and attenuation rate, and decreased responsivity, which verifies the advantage of the sputtering-annealing process of the present invention in forming high-quality ohmic contacts.

[0076] (5) GQDs doping contribution is clear: The responsivity and photo-dark current ratio of Comparative Example 6 (without GQDs) are lower than those of Example 2, indicating that GQDs doping has a positive contribution to synergistic effect by reducing the contact barrier and improving the conductivity / transmittance of ITO.

[0077] (6) The h-BN interface buffer layer makes a clear contribution: Example 1 (without h-BN) is slightly inferior to Example 2 (with h-BN) in terms of dark current, attenuation rate and responsivity, indicating that the h-BN buffer layer further improves ohmic contact and long-term stability by passivating interface dangling bonds and reducing defect states.

[0078] (7) In summary, Example 2 (ITO transparent interdigitated electrode + GQDs doping + h-BN buffer layer + Ti / Cr / Au lead-out + SiO / Si3N4 composite passivation) achieved the best overall performance: responsivity of approximately 0.21 A / W and UV / Vis suppression ratio of approximately 1.5 × 10⁻⁶. 3 The light-to-dark current ratio is approximately 7.5 × 10⁻⁶. 5 The rise / fall time is approximately 0.8 / 1.1 ms, and the long-term decay rate is approximately 3.2%, which is superior to all comparative and single optimization schemes.

[0079] The technical means disclosed in this invention are not limited to the above-described embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A GaN-based ITO transparent electrode ultraviolet photoelectric sensor, characterized in that, It includes a substrate, an n-type GaN epitaxial layer, an ITO transparent electrode layer, a metal lead-out layer, and a passivation layer, which are arranged sequentially from top to bottom. The metal lead-out layer is located at the end of the ITO transparent electrode layer.

2. The sensor according to claim 1, characterized in that: The substrate material is sapphire.

3. The sensor according to claim 1, characterized in that: The n-type GaN epitaxial layer is doped with Si at a doping concentration of 1×10⁻⁶. 18 cm -3 ~3×10 18 cm -3 .

4. The sensor according to claim 1, characterized in that: The metal lead-out layer comprises Ti / Au or Ti / Cr / Au.

5. The sensor according to claim 1, characterized in that: The ITO transparent electrode layer is doped with GQDs, and the mass fraction of GQDs doping is 0 to 0.5% based on the ITO layer mass.

6. The sensor according to claim 1, characterized in that: The passivation layer comprises SiO2 or a composite passivation layer of SiO2 and Si3N4.

7. The sensor according to claim 1, characterized in that: The electrode pattern of the ITO transparent electrode layer is an MSM interdigitated structure.

8. The sensor according to any one of claims 1-7, characterized in that: It also includes an h-BN interface buffer layer, which is disposed on the surface of the n-type GaN epitaxial layer and located below the ITO transparent electrode layer.

9. A method for fabricating a GaN-based ITO transparent electrode ultraviolet light sensor according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Clean the substrate and dry it for later use; S2. An n-type GaN epitaxial layer is grown on the substrate to obtain an n-GaN photosensitive layer; S3. An ITO thin film is prepared by depositing an ITO target at room temperature using a radio frequency magnetron sputtering process; Then, the MSM interdigitated electrode pattern is defined, and excess ITO is removed to form a transparent interdigitated electrode structure; then, annealing is performed to form an ITO / n-GaN ohmic contact. S4. A double metal layer is evaporated and deposited at the electrode tip as a lead-out electrode; S5. Deposit a passivation layer to complete sensor fabrication.

10. As described in claim 9, characterized in that: It also includes growing an h-BN interface buffer layer on the n-GaN surface.

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