An ultraviolet photodetector, its fabrication method and application

Abstract

This invention discloses an ultraviolet photodetector, its fabrication method, and its application. The ultraviolet photodetector comprises, in sequence: a substrate; a hydrophilic semiconductor layer disposed on the surface of the substrate; an ohmic contact electrode layer disposed on the surface of the hydrophilic semiconductor layer; an insulating dielectric layer disposed on the surface of the hydrophilic semiconductor layer, the insulating dielectric layer being separate from the ohmic contact electrode layer; and a metal contact electrode layer disposed on the surface of the insulating dielectric layer; the thickness of the insulating dielectric layer is 50-200 nm. This invention significantly improves the photoelectric performance of the device by inserting a thin dielectric layer between the metal contact electrode layer and the semiconductor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor-related technologies, and in particular to an ultraviolet photodetector, its fabrication method, and its application. Background Technology

[0002] In recent years, various structures of ultraviolet optoelectronic devices have been reported, such as pn junction, Schottky, metal-semiconductor-metal (MSM), and metal-semiconductor (MS) junctions. Among them, MS junction detectors have attracted widespread attention from many scholars due to their simple fabrication and ease of integration.

[0003] Currently reported high-performance metal-semiconductor junction detectors mostly employ metals with high work functions to increase the barrier height. However, due to the Fermi level pinning effect on semiconductor surfaces, the barrier height of metal-semiconductor junctions is often greatly affected by the manufacturing process. Furthermore, significant interdiffusion exists between the metal and semiconductor, impacting junction stability. Therefore, fabricating a thin dielectric layer with a high dielectric constant between the metal and semiconductor is an effective method to increase the barrier height and suppress the Fermi level pinning effect. However, fabricating high-quality ultrathin dielectric layers often requires high-vacuum equipment and complex fabrication processes.

[0004] Therefore, there is an urgent need to develop a high-performance ultraviolet optoelectronic device with a simple fabrication process. Summary of the Invention

[0005] The first technical problem to be solved by this invention is:

[0006] An ultraviolet photodetector is provided.

[0007] The second technical problem to be solved by this invention is:

[0008] A method for fabricating the ultraviolet photodetector is provided.

[0009] The third technical problem to be solved by this invention is:

[0010] Application of the ultraviolet photodetector.

[0011] To solve the first technical problem, the technical solution adopted by the present invention is as follows:

[0012] An ultraviolet photodetector includes, in sequence:

[0013] Substrate;

[0014] A hydrophilic semiconductor layer is disposed on the surface of the substrate;

[0015] An ohmic contact electrode layer is disposed on the surface of the hydrophilic semiconductor layer;

[0016] An insulating dielectric layer is disposed on the surface of the hydrophilic semiconductor layer, and the insulating dielectric layer is separated from the ohmic contact electrode layer.

[0017] A metal contact electrode layer is disposed on the surface of the insulating dielectric layer;

[0018] The thickness of the insulating dielectric layer is 50-200 nm.

[0019] This invention modifies the semiconductor layer to enhance the contact between the semiconductor layer and the precursor solution of the insulating dielectric layer, which is beneficial to the effective formation of the dielectric layer in the ultraviolet photodetector.

[0020] This invention inserts a thin dielectric layer between the metal contact electrode layer and the semiconductor. On the one hand, the addition of an insulating dielectric layer between the metal contact electrode layer and the semiconductor avoids direct contact between the two, thereby suppressing metal diffusion. On the other hand, since the conduction band of the insulating dielectric layer is higher than that of the hydrophilic semiconductor layer, the interface barrier is increased, which greatly improves the photoelectric performance of the device.

[0021] The thickness of the insulating dielectric layer is 50-200 nm. The thickness of the dielectric layer can be controlled by the number of spin-coating layers. The nanometer-scale thickness of the insulating dielectric layer increases the interfacial barrier between the hydrophilic semiconductor layer, the insulating dielectric layer, and the electrode layer. The thickness of the insulating dielectric layer affects the suppression of leakage current and the achievement of tunneling effect; if the insulating dielectric layer is too thin, it is not conducive to suppressing dark current, and if it is too thick, it will affect the tunneling of electrons through thin film defects. When the thickness of the insulating dielectric layer is 50-200 nm, the photoelectric performance of the ultraviolet photodetector of the present invention can be optimized.

[0022] According to one embodiment of the present invention, the substrate comprises at least one of silicon, sapphire, and silicon carbide. All of these substrates are capable of epitaxially growing hydrophilic semiconductor layers.

[0023] According to one embodiment of the present invention, the hydrophilic semiconductor layer includes at least one selected from GaN, ZnO, and SiC layers. The hydrophilic semiconductor layer can be selected from any material whose conductivity at room temperature is between that of a conductor and an insulator.

[0024] According to one embodiment of the present invention, the metal electrode contact layer includes at least one of an Au electrode layer, an Ag electrode layer, and an Al electrode layer.

[0025] According to one embodiment of the present invention, the ohmic contact electrode layer includes at least one of a Ti / Al electrode and a Ti / Al / Ti / Au electrode. The Ti / Al electrode is a two-layer metal stacked structure; the Ti / Al / Ti / Au electrode is a four-layer metal stacked structure.

[0026] The resistivity of the Ti / Al composite electrode is only 1 / 10 that of pure Ti; furthermore, adding a Ti / Au protective layer to the Ti / Al surface ensures that the Al layer does not spheroidize or oxidize at high temperatures, making the ohmic contact electrode layer more stable and reliable, thereby further improving the ohmic contact characteristics. This invention maximizes the reduction of interface resistance through the selection of the aforementioned ohmic contact electrode layer.

[0027] According to one embodiment of the present invention, the thickness of the hydrophilic semiconductor layer is 4-6 μm. The thickness of the hydrophilic semiconductor layer can be controlled by controlling the growth and deposition time; the present invention suppresses leakage current and regulates tunneling effect by adjusting the thickness of the hydrophilic semiconductor layer. When the thickness of the hydrophilic semiconductor layer is 4-6 μm, its carrier concentration at room temperature ranges from 1 × 10⁻⁶. 15 -1×10 18 cm -3 .

[0028] According to one embodiment of the present invention, the thickness of the metal contact electrode layer is 50-200 nm. The thickness of the metal contact electrode layer is greater than the thickness of the insulating dielectric layer, thereby increasing the interface barrier.

[0029] According to one embodiment of the present invention, the thickness of the ohmic contact electrode layer is 50-200 nm.

[0030] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0031] 1. The present invention inserts a thin dielectric layer between the metal contact electrode layer and the semiconductor. On the one hand, the addition of an insulating dielectric layer between the metal contact electrode layer and the semiconductor avoids direct contact between the two, thereby suppressing metal diffusion. On the other hand, since the conduction band of the insulating dielectric layer is higher than that of the hydrophilic semiconductor layer, the interface barrier is increased, thereby significantly improving the photoelectric performance of the device.

[0032] 2. The thickness of the insulating dielectric layer in this invention is 50-200 nm. The thickness of the dielectric layer can be controlled by the number of spin-coating layers. The nanometer-scale thickness of the insulating dielectric layer increases the interfacial barrier between the hydrophilic semiconductor layer, the insulating dielectric layer, and the electrode layer. The thickness of the insulating dielectric layer affects the suppression of leakage current and the achievement of tunneling effect; if the insulating dielectric layer is too thin, it is not conducive to suppressing dark current, and if it is too thick, it will affect the tunneling of electrons through thin film defects. When the thickness of the insulating dielectric layer is 50-200 nm, the photoelectric performance of the ultraviolet photodetector of this invention can be optimized.

[0033] 3. The ultraviolet photodetector of the present invention exhibits a light / dark current ratio exceeding four orders of magnitude under a -6V bias voltage and 330nm ultraviolet light irradiation. Furthermore, this ultraviolet photodetector also displays high efficiency (>10000%) and high response characteristics.

[0034] To solve the second technical problem, the technical solution adopted by the present invention is as follows:

[0035] A method for preparing the ultraviolet photodetector includes the following steps:

[0036] S1. An epitaxial semiconductor layer is grown on the substrate and then subjected to hydrophilic treatment to obtain the hydrophilic semiconductor layer.

[0037] S2 prepares an insulating dielectric layer precursor solution and spin-coates it onto the surface of the hydrophilic semiconductor layer to form the insulating dielectric layer;

[0038] S3. The metal electrode contact layer is prepared on the insulating dielectric layer; the ohmic contact electrode layer is prepared on the hydrophilic semiconductor layer.

[0039] According to one embodiment of the present invention, the epitaxial growth includes at least one of molecular beam epitaxy, pulsed laser deposition, and organometallic chemical vapor deposition.

[0040] According to one embodiment of the present invention, the hydrophilic treatment includes hydrophilic treatment of the semiconductor layer in an ozone cleaner, thereby enhancing the contact between the semiconductor layer and the precursor solution of the insulating dielectric layer.

[0041] According to one embodiment of the present invention, in step S1, the grown hydrophilic semiconductor layer is subjected to cleaning and drying operations.

[0042] According to one embodiment of the present invention, the cleaning process is as follows: the hydrophilic semiconductor layer is ultrasonically cleaned sequentially with acetone, ethanol and deionized water, each step lasting 10-15 minutes.

[0043] According to one embodiment of the present invention, the rotation speed is set to 2000-4000 rpm and the time is 20-40 s during the spin coating process.

[0044] According to one embodiment of the present invention, the metal electrode contact layer and the ohmic contact electrode layer can be prepared by vacuum evaporation or magnetron sputtering.

[0045] According to one embodiment of the present invention, the preparation of the insulating dielectric layer precursor solution includes the following steps:

[0046] The precursor material is dissolved, heated, allowed to stand, and then filtered to obtain the precursor solution of the insulating dielectric layer.

[0047] According to one embodiment of the present invention, the preparation of the insulating dielectric layer precursor solution includes the following steps:

[0048] A1 Weigh 1-5g of precursor material, preferably hafnium chloride, and slowly add the precursor material to a beaker containing 20-100ml of deionized water.

[0049] A2. Place it on a magnetic stirrer, set the temperature to 80-120℃ and the speed to 400-800rpm, and heat and stir for 1-2 hours.

[0050] A3 should be left to stand at room temperature for 10-48 hours for natural aging;

[0051] A4 was filtered using a 0.22-0.45 μm filter to obtain the HfO2 precursor solution.

[0052] According to one embodiment of the present invention, when the precursor material is hafnium chloride, the reactions involved in preparing the precursor solution for the insulating dielectric layer include hydrolysis and aging polymerization to form a gel, specifically:

[0053] HfCl4 + H2O → Hf(OH)Cl3 + HCl;

[0054] Hf(OH)Cl3→HfOCl2+HCl;

[0055] Undissolved hafnium chloride powder was filtered out by vacuum filtration, and the precursor solution was obtained by vacuum filtration.

[0056] According to one embodiment of the present invention, the thickness of the dielectric layer is controlled by the number of spin coatings, and the thickness of one spin coating is 10-15 nm.

[0057] Preferably, the thickness of the insulating dielectric layer of the present invention is 50-200 nm, therefore the number of spin coatings is 3-20 times.

[0058] According to one embodiment of the present invention, step A2 further includes an annealing process after the spin coating operation; the constant temperature during the annealing process is 150-550℃, the heating rate during the annealing process is 3-8℃ / min, and the holding time is 1-2h.

[0059] Annealing is used to achieve complete pyrolysis of the precursor liquid.

[0060] According to one embodiment of the present invention, during the spin-coating process of the precursor solution for the insulating dielectric layer, the precursor solution to be deposited consists of HfOCl2·nH2O. After annealing, HfOCl2 decomposes and transforms into HfO2.

[0061] Another aspect of the present invention relates to the application of the ultraviolet photodetector in flame detection. This includes the ultraviolet photodetector described in the first aspect embodiment above. Since this application employs all the technical solutions of the ultraviolet photodetector of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0062] One of the technical solutions described above has at least one of the following advantages or beneficial effects:

[0063] 1. The method for preparing the precursor solution of the insulating dielectric layer according to the present invention is simple and convenient and can achieve mass production; the present invention spin-coates the precursor solution and then anneals it to fully pyrolyze the precursor solution.

[0064] 2. The ultraviolet detector prepared by the method of this invention exhibits excellent photoelectric performance, with a light / dark current ratio exceeding four orders of magnitude. Furthermore, this ultraviolet detector also displays high efficiency (>10000%) and high response characteristics.

[0065] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0066] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0067] Figure 1 This is a schematic diagram of the structure of the ultraviolet photodetector in Examples 1-9.

[0068] Figure 2 The UV-Vis absorption spectra of the GaN material used in the semiconductor layers of Examples 1-7 are shown.

[0069] Figure 3 The image shows the UV-Vis absorption spectra of the HfO2 material used in the insulating dielectric layer of Examples 1-9.

[0070] Figure 4 This is a test diagram of the photoelectric performance of the ultraviolet detector in Example 1.

[0071] Figure 5 This is a test diagram of the photoelectric performance of the ultraviolet detector in Example 2.

[0072] Figure 6 This is a test diagram of the photoelectric performance of the ultraviolet detector in Example 3.

[0073] Figure 7 The graph shows the responsivity and external quantum efficiency of the ultraviolet detector in Example 3.

[0074] Figure label:

[0075] 100 - Substrate, 200 - Hydrophilic semiconductor layer, 300 - Ohmic contact electrode layer, 400 - Insulating dielectric layer, 500 - Metallic contact electrode layer. Detailed Implementation

[0076] Embodiments of the present invention are described in detail below. Examples of the above embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0077] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0078] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of the present invention.

[0079] Example 1

[0080] An ultraviolet photodetector includes, in sequence:

[0081] Substrate 100;

[0082] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0083] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0084] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0085] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0086] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0087] The hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 50 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0088] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0089] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0090] S1. Epitaxially grow a GaN thin film on substrate 100 to form a semiconductor layer;

[0091] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0092] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0093] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0094] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0095] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0096] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0097] (3) Allow to age naturally at room temperature for 24 hours;

[0098] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0099] Example 2

[0100] An ultraviolet photodetector includes, in sequence:

[0101] Substrate 100;

[0102] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0103] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0104] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0105] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0106] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0107] In this embodiment, the hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 50 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0108] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0109] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0110] S1. Epitaxially grow a GaN thin film on substrate 100 to form a hydrophilic semiconductor layer 200;

[0111] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 300℃ for 1 h.

[0112] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0113] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0114] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0115] (1) First, weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0116] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0117] (3) Allow to age naturally at room temperature for 24 hours;

[0118] (4) Finally, the HfO2 precursor solution was prepared by vacuum filtration using a 0.45 μm filter.

[0119] Example 3

[0120] An ultraviolet photodetector includes, in sequence:

[0121] Substrate 100;

[0122] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0123] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0124] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0125] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0126] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0127] In this embodiment, the hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3The thickness of the insulating dielectric layer 400 is 100 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0128] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0129] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0130] S1. Epitaxially grow a GaN thin film on substrate 100 to form a hydrophilic semiconductor layer 200;

[0131] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 300℃ for 1 h.

[0132] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0133] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0134] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0135] (1) First, weigh 1.8g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0136] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0137] (3) Allow to age naturally at room temperature for 24 hours;

[0138] (4) Finally, the HfO2 precursor solution was prepared by vacuum filtration using a 0.45 μm filter.

[0139] Example 4

[0140] An ultraviolet photodetector includes, in sequence:

[0141] Substrate 100;

[0142] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0143] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0144] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0145] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0146] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al / Ti / Au electrode; and metal electrode contact layer is an Ag electrode.

[0147] The hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 100 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0148] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0149] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0150] S1. Epitaxially grow a GaN thin film on substrate 100 to form a semiconductor layer;

[0151] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0152] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0153] S4. A Ti / Al / Ti / Au electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0154] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0155] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0156] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0157] (3) Allow to age naturally at room temperature for 24 hours;

[0158] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0159] Example 5

[0160] An ultraviolet photodetector includes, in sequence:

[0161] Substrate 100;

[0162] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0163] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0164] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0165] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0166] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0167] The hydrophilic semiconductor layer 200 has a thickness of 6 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 100 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0168] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0169] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0170] S1. Epitaxially grow a GaN thin film on a substrate 100 layer to form a semiconductor layer;

[0171] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0172] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0173] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0174] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0175] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0176] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0177] (3) Allow to age naturally at room temperature for 24 hours;

[0178] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0179] Example 6

[0180] An ultraviolet photodetector includes, in sequence:

[0181] Substrate 100;

[0182] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0183] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0184] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0185] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0186] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0187] The hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 50 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0188] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0189] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0190] S1. Epitaxially grow a GaN thin film on a substrate 100 layer to form a semiconductor layer;

[0191] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0192] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0193] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0194] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0195] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0196] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0197] (3) Allow to age naturally at room temperature for 24 hours;

[0198] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0199] Example 7

[0200] An ultraviolet photodetector includes, in sequence:

[0201] Substrate 100;

[0202] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0203] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0204] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0205] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0206] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0207] The hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 200 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0208] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0209] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0210] S1. Epitaxially grow a GaN thin film on a substrate 100 layer to form a semiconductor layer;

[0211] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0212] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0213] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0214] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0215] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0216] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0217] (3) Allow to age naturally at room temperature for 24 hours;

[0218] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0219] Example 8

[0220] An ultraviolet photodetector includes, in sequence:

[0221] Substrate 100;

[0222] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0223] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0224] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0225] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0226] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a GaN thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0227] The hydrophilic semiconductor layer 200 has a thickness of 5 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 100 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0228] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0229] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0230] S1. Epitaxially grow a GaN thin film on a substrate 100 layer to form a semiconductor layer;

[0231] S2. The GaN substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the GaN substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between GaN and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the GaN film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0232] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0233] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0234] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0235] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0236] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0237] (3) Allow to age naturally at room temperature for 24 hours;

[0238] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0239] Example 9

[0240] An ultraviolet photodetector includes, in sequence:

[0241] Substrate 100;

[0242] A hydrophilic semiconductor layer 200 is disposed on the surface of the substrate 100;

[0243] Ohmic contact electrode layer 300, wherein the ohmic contact electrode layer 300 is disposed on the surface of the hydrophilic semiconductor layer 200;

[0244] An insulating dielectric layer 400 is disposed on the surface of the hydrophilic semiconductor layer 200, and the insulating dielectric layer 400 is separated from the ohmic contact electrode layer 300.

[0245] A metal contact electrode layer 500 is disposed on the surface of the insulating dielectric layer 400.

[0246] Among them, substrate 100 is a sapphire substrate; hydrophilic semiconductor layer 200 is a ZnO thin film layer; insulating dielectric layer 400 is an HfO2 thin film layer; metal contact electrode layer 500 is a Ti / Al electrode; and metal electrode contact layer is an Ag electrode.

[0247] The hydrophilic semiconductor layer 200 has a thickness of 4 μm and a carrier concentration range of 4.3 × 10⁻⁶ at room temperature. 17 cm -3 The thickness of the insulating dielectric layer 400 is 100 nm, the thickness of the ohmic contact electrode layer 300 is 100 nm, and the thickness of the metal contact electrode layer 500 is 100 nm.

[0248] The ultraviolet photodetector has the following structure: Figure 1 As shown.

[0249] The method for preparing the above-mentioned ultraviolet photodetector includes the following steps:

[0250] S1. Epitaxially grow a ZnO thin film on a substrate 100 layer to form a semiconductor layer;

[0251] S2. The ZnO substrate prepared in step S1 was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, each step lasting 15 min. Subsequently, the ZnO substrate underwent hydrophilic treatment in a UV ozone cleaner to enhance the contact between ZnO and the HfO2 precursor solution. The hydrophilic treatment time was 20 min. The HfO2 precursor solution was prepared using the sol-gel method and then spin-coated onto the upper surface of the ZnO film, followed by annealing to prepare the HfO2 layer. The spin-coating speed was set to 3000 rpm for 30 s, and the annealing temperature was set to 200℃ for 1 h.

[0252] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0253] S4. A Ti / Al electrode is prepared on the surface of the hydrophilic semiconductor layer 200 by vacuum evaporation.

[0254] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0255] (1) Weigh 1.3g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0256] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0257] (3) Allow to age naturally at room temperature for 24 hours;

[0258] (4) Use a 0.45μm filter to filter and obtain HfO2 precursor solution.

[0259] Comparative Example

[0260] A non-hydrophilic ultraviolet photodetector, comprising:

[0261] Substrate;

[0262] A semiconductor layer is disposed on the surface of the substrate;

[0263] An ohmic contact electrode layer is disposed on the surface of the semiconductor layer;

[0264] An insulating dielectric layer is disposed on the surface of the semiconductor layer, and the insulating dielectric layer is separated from the ohmic contact electrode layer.

[0265] A metal contact electrode layer is disposed on the surface of the insulating dielectric layer.

[0266] The substrate is a sapphire substrate; the semiconductor layer is a GaN thin film layer; the insulating dielectric layer is an HfO2 thin film layer; the metal contact electrode layer is a Ti / Al electrode; and the metal electrode contact layer is an Ag electrode.

[0267] In this comparative example, the semiconductor layer thickness is 4 μm, and its carrier concentration at room temperature ranges from 4.3 × 10⁻⁶. 17 cm -3 The thickness of the insulating dielectric layer is 100 nm, the thickness of the ohmic contact electrode layer is 100 nm, and the thickness of the metal contact electrode layer is 100 nm.

[0268] The method for preparing the above-mentioned non-hydrophilic ultraviolet photodetector includes the following steps:

[0269] S1. Epitaxially grow a GaN thin film on the substrate to form a hydrophilic semiconductor layer;

[0270] S2. The GaN substrate prepared in step S1 is not subjected to hydrophilic treatment. Then, an HfO2 precursor solution is prepared by sol-gel method and spin-coated onto the upper surface of the GaN film, followed by annealing to prepare an HfO2 layer. The spin-coating speed is set to 3000 rpm and the time is 30 s. The annealing temperature is set to 300℃ and the holding time is 1 h.

[0271] S3. An Ag electrode is prepared on the upper surface of the HfO2 layer prepared in step S2 by vacuum evaporation.

[0272] S4. Prepare Ti / Al electrodes on the surface of the hydrophilic semiconductor layer by vacuum evaporation.

[0273] The specific preparation process of the HfO2 precursor solution in step S2 above is as follows:

[0274] (1) First, weigh 1.8g of hafnium chloride on an electronic balance and slowly add it to a beaker containing 50ml of deionized water;

[0275] (2) Place it on a magnetic stirrer, set the temperature to 80℃ and the speed to 500rpm, and heat and stir for 1 hour;

[0276] (3) Allow to age naturally at room temperature for 24 hours;

[0277] (4) Finally, the HfO2 precursor solution was prepared by vacuum filtration using a 0.45 μm filter.

[0278] Performance testing:

[0279] The GaN material used in the semiconductor layers of Examples 1-9 was subjected to ultraviolet-visible absorption spectroscopy tests, and the test results are as follows: Figure 2 As shown. From Figure 2 It is known that the band gap of GaN material is 3.4 eV. The ultraviolet-visible absorption spectra of the HfO2 material used in the insulating dielectric layers of Examples 1-8 were measured, and the results are as follows: Figure 3 ,from Figure 3 It is known that the band gap of HfO2 material is 5.8 eV. The conduction bands of GaN and HfO2 have high potential barriers, which is the main reason for the low dark current. However, the valence bands of GaN and HfO2 have low potential barriers, which are conducive to hole tunneling under high voltage conditions.

[0280] The photoelectric performance of the ultraviolet detectors prepared in Examples 1-4 was tested. The light / dark current ratio of the ultraviolet photodetectors was tested in the dark and under 330nm ultraviolet light irradiation. The test results are as follows: Figure 4-6 As shown in the figure. The horizontal axis represents voltage, and the vertical axis represents current. From... Figure 4 It can be seen that the fabricated GaN MIS tunnel junction ultraviolet detector exhibits light and dark currents of 3.2 mA and 1.5 μA, respectively, under 330 nm ultraviolet light irradiation, with a light / dark current ratio exceeding three orders of magnitude. From Figure 5 It can be seen that the dark current of the fabricated GaN MIS tunnel junction ultraviolet detector under 330nm ultraviolet light irradiation is similar to that of the detector. Figure 4 Compared to the previous model, this represents a reduction of approximately two orders of magnitude, while the light / dark current ratio exceeds three orders of magnitude. Figure 6 It can be seen that the light and dark currents of the fabricated GaN MIS tunnel junction ultraviolet detector under 330nm ultraviolet light irradiation are 4.3mA and 0.08μA, respectively, and the light / dark current ratio exceeds 4 orders of magnitude.

[0281] The responsivity and external quantum efficiency of the GaN-based MIS tunnel junction ultraviolet detector prepared in Example 3 were tested. Figure 7 As shown in the figure, the horizontal axis represents wavelength, and the vertical axes represent the responsivity and external quantum efficiency percentages, respectively. Figure 7 It can be seen that the device has a responsivity of 40 A / W under -6V bias and 330nm ultraviolet light irradiation, and an external quantum efficiency of over 10000%, demonstrating excellent optoelectronic performance.

[0282] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An ultraviolet photodetector, characterized in that: Including the following settings in sequence: Substrate; A hydrophilic semiconductor layer is disposed on the surface of the substrate; An ohmic contact electrode layer is disposed on the surface of the hydrophilic semiconductor layer; An HfO2 insulating dielectric layer is disposed on the surface of the hydrophilic semiconductor layer, and the HfO2 insulating dielectric layer is separated from the ohmic contact electrode layer. A metal contact electrode layer is disposed on the surface of the HfO2 insulating dielectric layer; The thickness of the insulating dielectric layer is 50-200 nm; The conductive band of the insulating dielectric layer is larger than that of the hydrophilic semiconductor layer; The hydrophilic semiconductor layer is a GaN layer with a thickness of 4-6 μm, and it has undergone ozone hydrophilic treatment.

2. The ultraviolet photodetector according to claim 1, characterized in that: The ohmic contact electrode layer includes at least one of Ti / Al electrode and Ti / Al / Ti / Au electrode.

3. The ultraviolet photodetector according to claim 1, characterized in that: The thickness of the metal contact electrode layer is 50-200 nm.

4. A method for preparing an ultraviolet photodetector as described in any one of claims 1 to 3, characterized in that: Includes the following steps: S1. An epitaxial semiconductor layer is grown on the substrate and then subjected to hydrophilic treatment to obtain the hydrophilic semiconductor layer. S2 prepares an insulating dielectric layer precursor solution and spin-coates it onto the surface of the hydrophilic semiconductor layer to form the insulating dielectric layer; S3. The metal electrode contact layer is prepared on the insulating dielectric layer; the ohmic contact electrode layer is prepared on the hydrophilic semiconductor layer.

5. The method according to claim 4, characterized in that: The epitaxial growth includes at least one of molecular beam epitaxy, pulsed laser deposition, and organometallic chemical vapor deposition.

6. The method according to claim 4, characterized in that: The preparation of the insulating dielectric layer precursor solution includes the following steps: The precursor material is dissolved, heated, allowed to stand, and then filtered to obtain the precursor solution of the insulating dielectric layer.

7. The method according to claim 4, characterized in that: In step S2, after the spin coating operation, an annealing process is also included; the constant temperature during the annealing process is 150-550℃, and the holding time is 1-2h.

8. The application of an ultraviolet photodetector as described in any one of claims 1 to 3 in flame detection.

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