Solar blind ultraviolet detector and manufacturing method thereof

Abstract

The invention relates to a solar blind ultraviolet detector and a manufacturing method thereof. The solar blind ultraviolet detector sequentially comprises a back electrode, a P-type silicon carbide substrate, a first tunneling oxide layer, an i-type wide band gap material layer, a second tunneling oxide layer, an N-type gallium oxide layer and a surface electrode. The P-type silicon carbide substrate, the i-type wide band gap material layer and the N-type gallium oxide layer form a pin heterojunction, electrons and holes can be limited in the i-type wide band gap material layer, and carrier collection is facilitated. Moreover, the first tunneling oxide layer can effectively inhibit the interface state between the P-type silicon carbide substrate and the i-type wide bandgap material layer, and the second tunneling oxide layer can effectively inhibit the interface state between the i-type wide bandgap material layer and the N-type gallium oxide layer, thereby reducing the non-radiative recombination of carriers between the interfaces, and improving the performance of the device. The interface recombination current (the main source of the dark current) is significantly inhibited, the dark current is significantly reduced, and the detection sensitivity and the signal-to-noise ratio are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically, to a solar-blind ultraviolet detector and its manufacturing method. Background Technology

[0002] Solar-blind ultraviolet detectors have important applications in flame detection, missile early warning, ultraviolet communication, and environmental monitoring. Traditional solar-blind ultraviolet detectors mostly use wide-bandgap semiconductor materials such as gallium nitride (GaN) and silicon carbide (SiC), but they suffer from problems such as large dark current, slow response speed, and poor process compatibility. In recent years, gallium oxide (Ga2O3) has become a research hotspot due to its ultra-wide bandgap (~4.9 eV) and excellent ultraviolet absorption characteristics.

[0003] Currently, solar-blind ultraviolet detectors using gallium oxide are typically constructed by directly epitaxially growing gallium oxide on a silicon carbide substrate. However, due to the significant lattice mismatch between the two materials and the presence of numerous defects at the interface, the detector suffers from high dark current and limited response speed. Summary of the Invention

[0004] Therefore, it is necessary to provide a solar-blind ultraviolet detector and its fabrication method to address the above problems, so as to reduce the dark current of the solar-blind ultraviolet detector and improve the response speed.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A solar-blind ultraviolet detector, comprising:

[0007] A P-type silicon carbide substrate, wherein a back electrode is disposed on the back side of the P-type silicon carbide substrate;

[0008] A first tunneling oxide layer is located on the front side of the P-type silicon carbide substrate;

[0009] An i-type wide bandgap material layer is located on the surface of the first tunneling oxide layer;

[0010] A second tunneling oxide layer is located on the surface of the type I wide bandgap material layer;

[0011] An N-type gallium oxide layer is located on the surface of the second tunneling oxide layer;

[0012] A surface electrode, wherein the surface electrode is located on the surface of the N-type gallium oxide layer.

[0013] In one embodiment, both the first tunneling oxide layer and the second tunneling oxide layer are made of silicon dioxide.

[0014] In one embodiment, the thickness of both the first tunneling oxide layer and the second tunneling oxide layer is 0.5 nm to 2 nm.

[0015] In one embodiment, the material used to fabricate the i-type wide bandgap material layer is silicon carbide, aluminum nitride, or diamond.

[0016] In one embodiment, the thickness of the i-type wide bandgap material layer is 100nm~5000nm.

[0017] In one embodiment, the thickness of the N-type gallium oxide layer is 200 nm to 5000 nm.

[0018] Another embodiment discloses a method for manufacturing a solar-blind ultraviolet detector, comprising:

[0019] A P-type silicon carbide substrate is provided, and the front and back sides of the P-type silicon carbide substrate are pretreated.

[0020] A first tunneling oxide layer is deposited on the front side of the P-type silicon carbide substrate;

[0021] A type I wide bandgap material layer is epitaxially grown on the surface of the first tunneling oxide layer;

[0022] A second tunneling oxide layer is deposited on the surface of the type-i wide bandgap material layer;

[0023] An N-type gallium oxide layer is epitaxially grown on the surface of the second tunneling oxide layer;

[0024] A surface electrode is formed on the surface of the N-type gallium oxide layer, and a back electrode is formed on the back side of the P-type silicon carbide substrate.

[0025] One embodiment includes a pretreatment process for the front and back sides of the P-type silicon carbide substrate, comprising:

[0026] The front and back sides of the P-type silicon carbide substrate are cleaned using the RCA process;

[0027] The front and back sides of the P-type silicon carbide substrate are subjected to in-situ high-temperature hydrogen treatment.

[0028] In one embodiment, the first tunneling oxide layer and the second tunneling oxide layer are deposited using an ALD process.

[0029] In one embodiment, the i-type wide bandgap material layer and the N-type gallium oxide layer are epitaxially grown using MOCVD or MBE processes.

[0030] Compared with existing technologies, the solar-blind ultraviolet detector disclosed in this invention comprises a pin heterojunction consisting of a P-type silicon carbide substrate, an i-type wide bandgap material layer, and an N-type gallium oxide layer. This confines electrons and holes within the i-type wide bandgap material layer, facilitating carrier collection. Furthermore, the first tunneling oxide layer effectively suppresses interface states between the P-type silicon carbide substrate and the i-type wide bandgap material layer, while the second tunneling oxide layer effectively suppresses interface states between the i-type wide bandgap material layer and the N-type gallium oxide layer. This reduces non-radiative recombination of carriers at each interface, significantly suppresses interface recombination current (the main source of dark current), significantly reduces dark current, and improves detection sensitivity and signal-to-noise ratio.

[0031] Meanwhile, the first and second tunneling oxide layers can provide quantum tunneling transport channels, suppress surface leakage current and interface trap trapping, isolate parasitic current paths between the highly doped region and the intrinsic region, reduce the slow release current (tailing effect) caused by interface traps, promote rapid carrier transport, and improve response speed.

[0032] In addition, the first and second tunneling oxide layers also have interface passivation capabilities, which can improve the resistance to environmental interference and enhance device stability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a solar-blind ultraviolet detector structure provided in an embodiment of the present invention;

[0034] Figure 2 This is a flowchart illustrating a method for fabricating a solar-blind ultraviolet detector, as provided in an embodiment of the present invention.

[0035] In the figure, 1 is a P-type silicon carbide substrate; 2 is a first tunneling oxide layer; 3 is an i-type wide bandgap material layer; 4 is a second tunneling oxide layer; 5 is an N-type gallium oxide layer; 6 is a surface electrode; and 7 is a back electrode. Detailed Implementation

[0036] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0038] One embodiment of the present invention discloses a solar-blind ultraviolet detector, such as... Figure 1 As shown, it includes:

[0039] P-type silicon carbide substrate 1, wherein a back electrode 7 is disposed on the back side of the P-type silicon carbide substrate 1;

[0040] The first tunneling oxide layer 2 is located on the front side of the P-type silicon carbide substrate 1.

[0041] Type I wide bandgap material layer 3, wherein the type I wide bandgap material layer 3 is located on the surface of the first tunneling oxide layer 2;

[0042] The second tunneling oxide layer 4 is located on the surface of the type I wide bandgap material layer 3;

[0043] An N-type gallium oxide layer 5 is located on the surface of the second tunneling oxide layer 4;

[0044] The surface electrode 6 is located on the surface of the N-type gallium oxide layer 5.

[0045] The silicon carbide (SiC) substrate has a bandgap of approximately 3.26 eV (4H-SiC), corresponding to a cutoff wavelength of about 380 nm. It exhibits high transmittance in the ultraviolet region and can serve as a device support layer and ohmic contact layer. The i-type wide bandgap material layer is the main region for photogenerated carriers and exhibits strong absorption in solar-blind ultraviolet light (200 nm ~ 280 nm). The gallium oxide (GaO) substrate has a bandgap of approximately 4.8 eV ~ 4.9 eV (β-Ga2O3), corresponding to a cutoff wavelength of 250 nm ~ 255 nm, perfectly covering the solar-blind band. The N-type gallium oxide layer is unresponsive to visible and near-infrared light from sunlight, but sensitive only to solar-blind ultraviolet light, providing intrinsic wavelength selectivity. The solar-blind ultraviolet detector disclosed in this invention comprises a p-type silicon carbide substrate 1, an i-type wide bandgap material layer, and an N-type gallium oxide layer forming a pin heterojunction. This confines electrons and holes within the i-type wide bandgap material layer, facilitating carrier collection.

[0046] A pin heterojunction, consisting of a p-type silicon carbide substrate, an i-type wide bandgap material layer, and an n-type gallium oxide layer, suffers from lattice mismatch and polarity mismatch between its layers, easily generating interface states. These interface states typically serve as nonradiative recombination centers for charge carriers. If the interface state density is high, charge carriers are easily trapped and undergo nonradiative recombination (e.g., phonon emission), leading to a loss of effective signal current. This invention addresses this by placing a first tunneling oxide layer between the p-type silicon carbide substrate and the i-type wide bandgap material layer, and a second tunneling oxide layer between the i-type wide bandgap material layer and the n-type gallium oxide layer. This achieves interlayer valence bond saturation (O atoms bond with uncoordinated bonds in Si and Ga) and dipole shielding (the built-in electric field of the oxide layer cancels the interface dipole moment), reducing the interface state density from 10... 12 cm -2 eV -1 Reduced to 10 10 cm -2 eV -1 The magnitude of the decrease in interface state density directly reduces the nonradiative recombination probability of electron-hole pairs at the interface.

[0047] It is evident that the introduction of the first and second tunneling oxide layers reduces the interface state density. According to the Shockley-Reid-Hall (SRH) recombination theory, the interface state density N... t With composite current I rec They are positively correlated. As the interface state density decreases, the dark current density can increase from mA / cm². 2 Reduced to nA / cm 2 .

[0048] Because the signal-to-noise ratio (SNR) is related to the signal current (I) signal and dark current I dark The relationship is: SNR∝ It is evident that as dark current decreases, the signal-to-noise ratio significantly improves. Simultaneously, reduced interfacial recombination allows more photogenerated carriers to participate in signal formation, enhancing quantum efficiency and responsivity. Ultimately, this manifests as increased sensitivity (reduced minimum detectable power) and expanded dynamic range for solar-blind ultraviolet detectors under low-light conditions.

[0049] In traditional devices, carriers trapped by light traps are slowly released after illumination ends, forming a current "tail" that severely slows down the response speed. In this embodiment of the invention, the first and second tunneling oxide layers provide quantum tunneling transport channels, suppressing surface leakage current and interface trap trapping, isolating parasitic current paths between the highly doped region and the intrinsic region, and enabling the photogenerated current to be established and disappear instantly with illumination. This reduces the slow release current (tail effect) caused by interface traps, promotes rapid carrier transport, improves the response speed, and ensures that the solar-blind ultraviolet detector can respond instantly to rapidly changing ultraviolet signals.

[0050] Furthermore, both the first and second tunneling oxide layers possess interface passivation capabilities, playing a crucial "protective shield" role in enhancing the long-term operational stability and environmental tolerance of the device. Through interface passivation, they reduce the density of fixed and mobile charges at the interface, preventing the intrusion of external charges or the accumulation of internal charges at the interface, thus preventing the formation of an unstable built-in electric field. This stable electrical environment directly translates into enhanced device stability. Moreover, interface passivation repairs broken lattice bonds, reducing the generation of stress concentration points. This allows the device to maintain structural integrity and resist performance degradation even under temperature cycling or high-power loads. Therefore, the interface passivation capability of the first and second tunneling oxide layers improves the device's resistance to environmental interference and enhances its stability.

[0051] In one embodiment, both the first and second tunneling oxide layers are made of silicon dioxide. Silicon dioxide possesses extremely high insulation and density. As a tunneling layer, its high resistivity effectively blocks DC leakage current, while its dense amorphous network structure effectively prevents impurity diffusion and ion migration. Moreover, silicon dioxide exhibits excellent interface passivation capabilities, forming relatively stable interfaces with both silicon-based materials (such as SiC) and oxide materials (such as Ga2O3), and significantly reducing the interface state density through dangling bonds on the oxygen-saturated semiconductor surface. Furthermore, since both SiC and Ga2O3 are wide-bandgap semiconductors, using silicon dioxide, which is also a wide-bandgap material, as an intermediate layer avoids the potential for light absorption loss or increased thermally excited carriers that might result from introducing narrow-bandgap materials, ensuring high transmittance and low noise in the solar-blind ultraviolet band.

[0052] In addition, the materials used to fabricate the first and second tunneling oxide layers can also be high-k dielectric materials such as hafnium dioxide, titanium dioxide, tantalum pentoxide, aluminum oxide, or silicon nitride.

[0053] In one embodiment, the thickness of both the first and second tunneling oxide layers is 0.5 nm to 2 nm. Within this range, the film's density and insulation are ensured, preventing leakage and short circuits, and providing a guarantee for reducing dark current. Simultaneously, it ensures the effective occurrence of the quantum tunneling effect, maintaining a high-speed transport channel for charge carriers and avoiding the collapse of response speed. Preferably, the thickness of both the first and second tunneling oxide layers is 1.0 nm to 1.5 nm, such as 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, or 1.5 nm. The thicknesses of the two tunneling oxide layers can be the same or different, but both are within the range of 0.5 nm to 2 nm. Moreover, within this range, high-quality chemical bonding can be formed, effectively passivating interface states (repairing dangling bonds). At the same time, the tunneling resistance at this thickness is within an acceptable range and will not significantly reduce the photocurrent collection efficiency. Furthermore, in atomic layer deposition (ALD) or PECVD processes, a thickness range of 1.0 nm to 1.5 nm allows for some thickness variation without causing catastrophic changes in device performance.

[0054] In one embodiment, the material used to fabricate the i-type wide bandgap material layer is silicon carbide, aluminum nitride, or diamond.

[0055] Silicon carbide has a bandgap of 3.26 eV, corresponding to a wavelength of approximately 380 nm, which falls within the ultraviolet-A band. In this structure, silicon carbide is used as the type-i wide bandgap material layer, primarily absorbing ultraviolet light with wavelengths between 300 nm and 380 nm, making it suitable for wide-band ultraviolet detection. Aluminum nitride has a bandgap as high as 6.2 eV, corresponding to an absorption edge of around 200 nm, which falls precisely in the vacuum ultraviolet (VUV) band. Using aluminum nitride as the type-i wide bandgap material layer, the entire detector will be sensitive to light with wavelengths less than 200 nm and completely unresponsive to visible and near-infrared light (extremely high ultraviolet / visible suppression ratio), making it suitable for vacuum ultraviolet detection (such as space exploration and plasma monitoring) and possessing extremely strong anti-interference capabilities. Diamond has a bandgap of 5.47 eV, corresponding to an absorption wavelength of approximately 225 nm, also falling within the solar-blind band. Diamond has extremely high thermal conductivity (more than 10 times that of Si) and extremely high breakdown electric field, making it suitable for solar-blind detection in extreme environments such as high temperature and high radiation.

[0056] In one embodiment, the thickness of the i-type wide bandgap material layer is 100 nm to 5000 nm. Preferably, the thickness of the i-type wide bandgap material layer is 100 nm to 500 nm, such as 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm. Within this range, the carrier transit time is extremely short (<1 ns), suitable for the detection of high-frequency modulated optical signals. Alternatively, the thickness of the i-type wide bandgap material layer is 500 nm to 2000 nm, such as 500 nm, 800 nm, 1200 nm, 1600 nm, or 2000 nm. At this thickness, the material can achieve an absorption rate of over 99% for solar-blind ultraviolet light, while the carrier transit time remains in the nanosecond range. Alternatively, the thickness of the type-i wide bandgap material layer can be 2000nm to 5000nm, such as 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm, or 5000nm. Within this range, high series resistance exists, and the internal electric field is extremely strong under the same bias voltage. The combined effect of the first and second tunneling oxide layers in lowering the contact barrier can induce a gain bandwidth effect, giving the solar-blind ultraviolet detector higher sensitivity.

[0057] In one embodiment, the thickness of the N-type gallium oxide layer is 200 nm to 5000 nm. Preferably, the thickness of the N-type gallium oxide layer is 200 nm to 500 nm, such as 200 nm, 300 nm, 400 nm, or 500 nm. Within this range, the junction capacitance is small, suitable for high-frequency / high-speed detection, and full depletion can be achieved under low bias voltage, which helps reduce power consumption and is suitable for high-speed pulse detection and low-power wearable devices. Alternatively, the thickness of the N-type gallium oxide layer is 500 nm to 2000 nm, such as 500 nm, 700 nm, 1000 nm, 1300 nm, 1600 nm, or 2000 nm. Within this range, both light absorption of over 90% can be guaranteed and good crystal quality can be maintained, making it suitable for general-purpose solar-blind ultraviolet detectors and imaging arrays. Alternatively, the thickness of the N-type gallium oxide layer can be 2000nm~5000nm, such as 2000nm, 2600nm, 3200nm, 3800nm, 4400nm, or 5000nm. Within this range, higher reverse bias voltages can be applied without breakdown, thereby generating an avalanche multiplication effect (APD mode) in the depletion region or utilizing defect states to generate grating gain. It also reduces the peak electric field near the electrodes and suppresses tunneling dark current, making it suitable for single-photon detection, long-distance ultraviolet communication, and low-light imaging.

[0058] In one embodiment, the surface electrode and back electrode are made of metallic materials such as Ni / Au or Ti / Al. For example, the surface electrode can be a Ni / Au electrode, which makes a Schottky contact with the N-type gallium oxide layer and serves as the collector electrode of the light incident surface, balancing light transmittance and rectification characteristics. The back electrode is a Ti / Al electrode, which serves as the ground electrode on the back side of the P-type silicon nitride substrate, providing an extremely low resistance circuit. The surface electrode and back electrode can be alloyed to form excellent ohmic contacts, ensuring that photogenerated carriers can quickly form a circuit and improving the response speed.

[0059] Another embodiment discloses a method for fabricating a solar-blind ultraviolet detector, such as Figure 2 As shown, it includes:

[0060] Step S1: Provide a P-type silicon carbide substrate and preprocess the front and back sides of the P-type silicon carbide substrate.

[0061] Step S2: Deposit a first tunneling oxide layer on the front side of the P-type silicon carbide substrate.

[0062] Step S3: Epitaxially grow an i-type wide bandgap material layer on the surface of the first tunneling oxide layer.

[0063] Step S4: Deposit a second tunneling oxide layer on the surface of the i-type wide bandgap material layer.

[0064] Step S5: An N-type gallium oxide layer is epitaxially grown on the surface of the second tunneling oxide layer.

[0065] Step S6: A surface electrode is formed on the surface of the N-type gallium oxide layer, and a back electrode is formed on the back side of the P-type silicon carbide substrate.

[0066] The solar-blind ultraviolet detector prepared using the method disclosed in this embodiment can reduce nonradiative recombination of charge carriers between interfaces by utilizing the first tunneling oxide layer and the second tunneling oxide layer, significantly suppressing the interface recombination current (the main source of dark current), significantly reducing dark current, and improving detection sensitivity and signal-to-noise ratio.

[0067] One embodiment includes a pretreatment process for the front and back sides of the P-type silicon carbide substrate, comprising:

[0068] The front and back sides of the P-type silicon carbide substrate are cleaned using the RCA process;

[0069] The front and back sides of the P-type silicon carbide substrate are subjected to in-situ high-temperature hydrogen treatment.

[0070] Cleaning not only removes impurities such as particles, organic contaminants, alkali metals, and transition metal ions from the surface of p-type silicon carbide substrates, but also removes the surface silica layer. High-temperature in-situ hydrogen treatment eliminates surface dangling bonds, forming atomically flat termination surfaces that provide a high-quality nucleation interface for subsequent epitaxial growth, while also suppressing interface state density and improving the interface quality between the subsequent oxide layer and SiC.

[0071] In one embodiment, the first and second tunneling oxide layers are formed using an ALD process. The ALD process employs a temperature of 200°C to 300°C, enabling atomic-level thickness control and an ultra-smooth interface.

[0072] In one embodiment, the i-type wide bandgap material layer and the N-type gallium oxide layer are epitaxially grown using MOCVD (metal-organic chemical vapor deposition) or MBE (molecular beam epitaxy). The growth temperature of the i-type wide bandgap material layer is 1500°C to 1600°C, and the growth temperature of the N-type gallium oxide layer is 600°C to 800°C.

[0073] The solar-blind ultraviolet detector and its manufacturing method disclosed in this invention will be described below through two specific embodiments.

[0074] Example 1

[0075] Example 1 discloses a solar-blind ultraviolet detector, such as Figure 1 As shown, it includes:

[0076] A P-type silicon carbide substrate 1 has a back electrode 7 on its back side, and the back electrode 7 is a Ti / Al composite metal electrode.

[0077] The first tunneling oxide layer 2 is made of silicon dioxide and has a thickness of 1.0 nm. It is located on the front side of the P-type silicon carbide substrate 1.

[0078] The i-type wide bandgap material layer 3 is made of intrinsic silicon carbide and has a thickness of 100 nm. It is located on the surface of the first tunneling oxide layer 2.

[0079] The second tunneling oxide layer 4 is made of silicon dioxide and has a thickness of 1.0 nm. It is located on the surface of the i-type wide bandgap material layer 3.

[0080] The N-type gallium oxide layer 5 has a thickness of 200 nm and is located on the surface of the second tunneling oxide layer 4.

[0081] The surface electrode 6 is made of Ni / Au composite metal and is located on the surface of the N-type gallium oxide layer 5.

[0082] Example 2

[0083] Example 2 discloses a method for fabricating a solar-blind ultraviolet detector, comprising:

[0084] Step S1: Provide a P-type silicon carbide substrate and preprocess the front and back sides of the P-type silicon carbide substrate.

[0085] The substrate is a 4H-SiC or 6H-SiC single crystal substrate with a (0001) crystal orientation and a P-type doping type (doped with Al or B). The P-type silicon carbide substrate has a thickness of 350μm to 500μm, is double-sided polished, and has a surface roughness Ra < 0.2nm.

[0086] The front and back sides of the P-type silicon carbide substrate were cleaned using the RCA process. A first cleaning solution (NH4OH:H2O2:H2O = 1:1:5 (volume ratio)) was used to clean for 10-15 minutes at 70°C-80°C, removing particulates and organic contaminants through an oxidation-complexation mechanism. A second cleaning solution (HCl:H2O2:H2O = 1:1:6) was used to clean for 10 minutes at 70°C-80°C, removing alkali metal and transition metal ions through complexation. A third cleaning solution (1-5% HF aqueous solution) was used to clean for 30-60 seconds to remove the silicon dioxide layer on the surface of the P-type silicon carbide substrate. The substrate was rinsed at least five times with ultrapure water and dried with nitrogen or by high-speed spin drying to prevent water residue.

[0087] The front and back sides of the p-type silicon carbide substrate were subjected to in-situ high-temperature hydrogen treatment. The cleaned p-type silicon carbide substrate was annealed in-situ at 1300°C under a high-purity H2 (99.999%) atmosphere and at normal pressure. During this process, H2 decomposes into active H atoms at high temperature, which react with C atoms on the SiC surface to generate volatile C atoms. x H y This process enables surface reconstruction. It eliminates surface dangling bonds, forming atomically flat Si termination surfaces, providing a high-quality nucleation interface for subsequent epitaxial growth. It also suppresses interface state density, improving the interface quality between the subsequent oxide layer and SiC.

[0088] Step S2: Deposit a first tunneling oxide layer (silicon dioxide layer) on the front side of the P-type silicon carbide substrate using atomic layer deposition (ALD) process.

[0089] In this process, tetraethyl orthosilicate (TEOS) is used as the silicon source, O3 is used as the oxygen source, the temperature is 200℃~300℃, and the thickness of the first tunneling oxide layer (silicon dioxide layer) is 1nm.

[0090] Step S3: An i-type wide bandgap material layer is epitaxially grown on the surface of the first tunneling oxide layer using a metal-organic chemical vapor deposition (MOCVD) process.

[0091] Propane (C3H8) was used as the carbon source, silane (SiH4) as the silicon source, H2 as the carrier gas, the temperature was 1500℃~1600℃ (high temperature is the key to ensuring the quality of SiC crystals), the pressure was 50Torr~100Torr, no special doping gases (such as N2 or NO for N-type, Al or B for p-type) were introduced, and the high-resistivity i-type was controlled by background doping. The thickness of the prepared i-type wide bandgap material layer was 100nm.

[0092] Since there is already SiO2 deposited by ALD below, this step requires controlling the heating rate and airflow to prevent SiO2 from reacting or interdiffusion with the SiC interface at high temperatures.

[0093] Step S4: Deposit a second tunneling oxide layer (silicon dioxide layer) on the surface of the i-type wide bandgap material layer using atomic layer deposition (ALD) process. This step is consistent with step S2, and the thickness of the formed second tunneling oxide layer (silicon dioxide layer) is 1 nm.

[0094] Step S5: An N-type gallium oxide layer is epitaxially grown on the surface of the second tunneling oxide layer using a metal-organic chemical vapor deposition (MOCVD) process.

[0095] Trimethylgallium (TMGa) was used as the gallium source, H2O as the oxygen source, and silane (SiH4) as the dopant source. An N-type gallium oxide layer was epitaxially grown in a temperature range of 600℃ to 800℃, and the thickness of the N-type gallium oxide layer was 200nm.

[0096] Step S6: A surface electrode is formed on the surface of the N-type gallium oxide layer, and a back electrode is formed on the back side of the P-type silicon carbide substrate. The surface electrode is a Ni / Au composite metal layer, and the back electrode is a Ti / Al composite metal layer.

[0097] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The terms "first" and "second" used in this document are for distinction only and are not intended to limit the content of this invention.

[0098] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A solar-blind ultraviolet detector, characterized in that, include: A P-type silicon carbide substrate, wherein a back electrode is disposed on the back side of the P-type silicon carbide substrate; A first tunneling oxide layer is located on the front side of the P-type silicon carbide substrate; An i-type wide bandgap material layer is located on the surface of the first tunneling oxide layer; A second tunneling oxide layer is located on the surface of the type I wide bandgap material layer; An N-type gallium oxide layer is located on the surface of the second tunneling oxide layer; A surface electrode, wherein the surface electrode is located on the surface of the N-type gallium oxide layer.

2. The solar-blind ultraviolet detector according to claim 1, characterized in that, Both the first tunneling oxide layer and the second tunneling oxide layer are made of silicon dioxide.

3. The solar-blind ultraviolet detector according to claim 2, characterized in that, The thickness of both the first tunneling oxide layer and the second tunneling oxide layer is 0.5 nm to 2 nm.

4. The solar-blind ultraviolet detector according to claim 1, characterized in that, The i-type wide bandgap material layer is made of silicon carbide, aluminum nitride, or diamond.

5. The solar-blind ultraviolet detector according to claim 4, characterized in that, The thickness of the i-type wide bandgap material layer is 100nm~5000nm.

6. The solar-blind ultraviolet detector according to claim 1, characterized in that, The thickness of the N-type gallium oxide layer is 200nm~5000nm.

7. A method for manufacturing a solar-blind ultraviolet detector, characterized in that, include: A P-type silicon carbide substrate is provided, and the front and back sides of the P-type silicon carbide substrate are pretreated. A first tunneling oxide layer is deposited on the front side of the P-type silicon carbide substrate; A type I wide bandgap material layer is epitaxially grown on the surface of the first tunneling oxide layer; A second tunneling oxide layer is deposited on the surface of the type-i wide bandgap material layer; An N-type gallium oxide layer is epitaxially grown on the surface of the second tunneling oxide layer; A surface electrode is formed on the surface of the N-type gallium oxide layer, and a back electrode is formed on the back side of the P-type silicon carbide substrate.

8. The method for manufacturing a solar-blind ultraviolet detector according to claim 7, characterized in that, The pretreatment process for the front and back sides of the P-type silicon carbide substrate includes: The front and back sides of the P-type silicon carbide substrate are cleaned using the RCA process; The front and back sides of the P-type silicon carbide substrate are subjected to in-situ high-temperature hydrogen treatment.

9. The method for manufacturing a solar-blind ultraviolet detector according to claim 7, characterized in that, The first tunneling oxide layer and the second tunneling oxide layer are deposited using the ALD process.

10. The method for manufacturing a solar-blind ultraviolet detector according to claim 7, characterized in that, The i-type wide bandgap material layer and the N-type gallium oxide layer are epitaxially grown using MOCVD or MBE processes.

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