Rare earth doped gallium oxide thin film, preparation method thereof and application of rare earth doped gallium oxide thin film in photoelectric integrated device

Abstract

The invention discloses a rare earth doped gallium oxide thin film, a preparation method thereof and application in a photoelectric integrated device, a Ga2O3-based solar blind ultraviolet detector has important application potential in the field of flame and arc detection, but the performance of the device is limited by high dark current. Meanwhile, integration of a plurality of photoelectric functions helps to reduce the size of the device and improve the feedback speed. Rare earth doping is an effective optimization strategy, and can improve the performance of a photoelectric device and endow the photoelectric device with an electroluminescent function. Therefore, an organic precursor decomposition strategy is developed to synthesize a rare earth doped Ga2O3 (Ga2O3: RE) thin film, and a Ga2O3: RE / SiO2 / p-Si heterojunction device is integrally constructed. Under the irradiation of 254 nm light, the responsivity, the detectivity and the response time of the device are 5.25 * 10 < 3 > mA W <-1 >, 3.67 * 10 < 14 > Jones and 50 microseconds respectively. The device has rare earth related electroluminescence under reverse voltage. The device integrates photoelectric detection and electroluminescence, can realize visualization of ultraviolet signals, and has high designability.

Description

Technical Field

[0001] This invention relates to the field of wide bandgap semiconductor material preparation and optoelectronic applications, specifically to a rare earth-doped gallium oxide thin film, its preparation method, and its application in optoelectronic integrated devices. Background Technology

[0002] Solar-blind ultraviolet (SBUV, wavelength range 200-280 nm) radiation is almost completely absorbed by the ozone layer in Earth's atmosphere, resulting in extremely low solar background noise on the Earth's surface within this wavelength range. This unique natural advantage provides an extremely high signal-to-noise ratio for photoelectric detection applications, giving it irreplaceable strategic value in military, civilian, and scientific research fields. Currently, solar-blind ultraviolet detectors are widely used in key areas such as space communication, missile early warning, ultraviolet imaging, and fire detection. With the rapid development of modern industry, aerospace, and defense technologies, the market demand for solar-blind ultraviolet detectors with high sensitivity, high stability, fast response speed, and low power consumption is becoming increasingly urgent, which has greatly promoted the research and development of new wide-bandgap semiconductor materials and their high-performance devices.

[0003] Gallium oxide (Ga2O3) has a large bandgap of approximately 4.8–4.9 eV, corresponding to the deep ultraviolet light absorption region. Furthermore, Ga2O3 possesses a high breakdown electric field strength (approximately 8 MV / cm), good thermal and chemical stability, enabling stable operation in extreme environments, making it an ideal material for constructing solar-blind ultraviolet detectors. Currently, various thin-film fabrication techniques have been reported for the growth of Ga2O3 films, including molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). However, Ga2O3 films prepared by these methods generally suffer from poor crystal quality and high intrinsic oxygen vacancy defect density. These defects easily form trapped states and leakage channels within the material, leading to high dark current and severely impacting the overall performance of the device. More importantly, photogenerated carriers are easily captured and released by these defects during transport, significantly reducing the device's response and recovery speeds.

[0004] To overcome the inherent defects of Ga2O3 thin films and improve device performance, doping engineering has proven to be an effective strategy. By introducing suitable dopants, the band structure, carrier concentration, and defect states of Ga2O3 can be precisely controlled. For example, introducing n-type dopants (such as Si and Sn) or p-type dopants (such as Mg) can effectively increase carrier concentration and mobility, while passivating oxygen vacancies and reducing the density of trapped states, thereby significantly reducing dark current and improving device response speed. Furthermore, unlike traditional dopants, rare earth (RE) elements have unique advantages in optoelectronics, mainly due to the unique electronic transition characteristics between 4f-4f or 4f-5d orbitals. These electronic transitions can generate narrowband light emission, showing great application potential in high-resolution displays and optical communications. Doping rare earth elements into Ga2O3 (Ga2O3:RE) can make it a highly efficient electroluminescence (EL) active layer, enabling the characteristic luminescence of rare earth ions through electric field excitation. For example, Er-doped Ga₂O₃ can produce green or near-infrared emission. These properties make Ga₂O₃:RE a promising candidate for constructing efficient and stable electroluminescent devices.

[0005] Furthermore, single-function photodetectors or light-emitting devices suffer from drawbacks such as response or feedback lag and high system complexity when facing complex application scenarios. For photodetectors and electroluminescent devices, the similar Si / SiO2 / Ga2O3:RE structure makes it possible to construct multifunctional integrated optoelectronic devices. Such integrated devices not only improve the system's integration and compactness but also enable real-time signal conversion and processing, holding promise for applications in novel information sensing and visualization display fields.

[0006] In summary, effective methods for synthesizing high-quality solar-blind ultraviolet detection materials and constructing multifunctional optoelectronic devices are still lacking. Furthermore, studying Ga2O3:RE thin films is not only an effective way to address the inherent defects of Ga2O3 materials and improve detector performance, but also crucial for developing multifunctional integrated optoelectronic devices with both detection and emission functions, utilizing the unique optical properties of rare earth elements, thus enabling information perception and visualization in complex application scenarios. Therefore, developing a simple, universal, and controllable method for preparing Ga2O3:RE materials and studying its photoelectric detection and EL performance has significant scientific and application value. Summary of the Invention

[0007] The present invention aims to provide a rare-earth-doped gallium oxide thin film, its preparation method, and its application in optoelectronic integrated devices. By employing a self-made organic precursor with good customizability and transferability, the controllable synthesis of Ga2O3 thin films was successfully achieved. Er doping effectively modulated the material properties and band structure of Ga2O3, thereby significantly improving the optoelectronic performance of the device. Under a reverse bias voltage of -1 V and irradiation with 254 nm ultraviolet light, the prepared device exhibits a high performance of 3.67 × 10⁻⁶. 14 Jones (Jones = cm Hz) 1 / 2 W -1 The device exhibits a high specific detectivity. Furthermore, it demonstrates rare-earth-related EL behavior under high reverse bias voltage. This device, integrating photodetection and EL functions, not only enables real-time conversion of solar-blind ultraviolet signals to visible signals but also provides an innovative solution for visualizing invisible signals.

[0008] A method for preparing rare-earth-doped gallium oxide thin films, the materials are mainly synthesized in four steps, such as... Figure 1 As shown: (1) ionizes into RE that is soluble in water 3+ (Rare earth ion) compounds, soluble in water, ionize to release Ga 3+ Deionized water was added dropwise to a mixture of the compound and PVA (polyvinyl alcohol), and the mixture was sonicated to dissolve it completely. The solution was then sealed and heated, and the heated solution was aged at room temperature to obtain a liquid-phase precursor. (2) Drop the liquid precursor into a petri dish and dry it to transform the liquid precursor solution into an organic film. The organic film contains Ga and RE precursors (PVA-Ga-RE). Peel it off from the petri dish to obtain a PVA-Ga-RE organic precursor film. Cut the PVA-Ga-RE organic precursor film into the required shape and place it in a dry environment for later use. (3) Place the PVA-Ga-RE organic precursor film on the substrate and heat it to make the organic precursor film adhere to the substrate; (4) The substrate covered with the PVA-Ga-RE organic precursor film is placed in a tube furnace with openings at both ends and heated at high temperature to obtain a Ga2O3 film.

[0009] Furthermore, in step (1), water-soluble substances ionize to produce RE. 3+ The compound is at least one of the following: RE 3+ Sulfuric acid compounds, chloride compounds, acetic acid compounds, and nitric acid compounds; RE 3+ The hydrates corresponding to sulfuric acid compounds, chlorides, acetic acid compounds, or nitrate compounds.

[0010] Furthermore, in step (1), Ga, which is soluble in water, ionizes. 3+ The compound is at least one of the following: Gallium nitrate, gallium chloride, gallium sulfate, gallium citrate; The hydrates of gallium nitrate, gallium chloride, gallium sulfate, and gallium citrate.

[0011] Further, in step (1), the degree of PVA hydrolysis is (86~90)%, the degree of polymerization is 1700~2500, the heating temperature after sealing is 80~95℃, the heating time is 30~90 minutes, and the solution aging time is 5~10 hours.

[0012] Furthermore, in step (1), RE 3+ For Er 3+ Eu 3+ and Tm 3+ At least one of them, RE 3+ Doping concentration of RE 3+ and Ga 3+ 1 mol% to 4 mol% of total molar amount per 1 to 3 mmol Ga 3+ 0.4~0.6g of PVA is required.

[0013] Furthermore, in step (2), the drying temperature of the liquid precursor is 70~98 ℃ and the drying time is 4~8 hours; the thickness of the PVA-Ga-RE organic precursor film is 3~30μm.

[0014] Further, in step (3), the substrate is a Si substrate, a Si substrate covered with SiO2, or a sapphire substrate; the heating temperature is 100~150 ℃, and the heating time is 3~10 minutes.

[0015] Furthermore, in step (4), the high-temperature heating temperature is 750~950 ℃ and the high-temperature heating time is 30~120 minutes.

[0016] The rare-earth-doped gallium oxide thin film obtained by the above preparation method.

[0017] The application of a rare-earth-doped gallium oxide thin film in optical integrated devices is as follows: S1. Prepare PVA-Ga-Zn organic precursor films and PVA-Ga-RE organic precursor films according to steps (1) and (2) of claim 1; S2. Heat treatment: PVA-Ga-RE organic precursor film and PVA-Ga-Zn organic precursor film are bonded together to obtain composite organic precursor film. The composite organic precursor film is placed on the substrate, with the PVA-Ga-RE organic precursor film in close contact with the substrate, and heated at 100~150 ℃ for 3~10 minutes. S3. Place the substrate covered with the composite organic precursor film in a tube furnace with openings at both ends and heat it at high temperature. S4. Coat the other side of the substrate with silver paste and dry at 130~150°C for 30~70 minutes to obtain the Ag metal back electrode.

[0018] Furthermore, in S1, the Ga doping amount in the PVA-Ga-Zn organic precursor film accounts for 3 mol% to 6 mol% of the total Ga and Zn content, with each 1 to 4 mmol Zn doping... 2+ 0.4~0.6g of PVA is required.

[0019] Furthermore, the thickness of both the PVA-Ga-Zn organic precursor film and the PVA-Ga-RE organic precursor film in S1 is 3~30 μm.

[0020] Furthermore, heat treatment in S2 refers to heating at 100~150 ℃ for 3~10 minutes.

[0021] Furthermore, the high-temperature heating temperature in S4 is 750~950 ℃, and the high-temperature heating time is 30~120 minutes.

[0022] Compared with the prior art, the present invention has the following significant advantages: (1) The thin film preparation process is simple and universal. This invention employs a liquid-phase precursor solution preparation method, which allows for the ionization of REs through dissolution. 3+ and Ga 3+By incorporating PVA as an organic precursor, the compound avoids expensive vacuum equipment and complex epitaxial growth processes (such as MBE), significantly reducing preparation costs and simplifying the operation process. The liquid-phase precursor is transformed into a peelable PVA-Ga-RE organic film, which can be cut into any shape as needed. This provides a high degree of customization in shape and size, offering great flexibility for subsequent device integration—something difficult to achieve with traditional thin film growth methods. Utilizing the melting properties of PVA, the organic precursor film is easily and firmly adhered to the target substrate. This "peel-attach" transfer mechanism overcomes the limitations of direct high-temperature growth on complex or large-area substrates, significantly improving film transfer efficiency and applicability, and providing a new approach for heterogeneous integration. Ga2O3 films can be obtained by high-temperature decomposition of the precursor in air, avoiding strict requirements for specific atmospheres (such as high vacuum or special reactive gases), further simplifying the process and reducing production costs.

[0023] (2) Improve the quality of thin film crystals and enhance the basic performance of devices. Traditional Ga2O3 thin films contain a large number of inherent oxygen vacancy defects, resulting in high dark current and poor performance. This invention optimizes the crystal growth process by doping with refractive acids (REs), reducing oxygen vacancy defects and trapped state density in the thin film, thereby lowering the dark current and improving the signal-to-noise ratio of the device. The reduction in defects means a lower probability of photogenerated carriers being trapped and released during transport, thus significantly improving carrier mobility and lifetime, and enhancing the performance of the photodetector.

[0024] (3) Utilizing the properties of rare earth elements to achieve multifunctional optoelectronic integration The unique 4f-4f or 4f-5d transition characteristics of rare earth elements endow doped Ga₂O₃ thin films with narrowband light emission capabilities. This makes it possible to develop high-resolution displays and high-efficiency optical communication devices. Ga₂O₃:RE thin films can serve as electroluminescent active layers, achieving the characteristic luminescence of rare earth ions through electric field excitation. The prepared rare earth-doped Ga₂O₃ thin films simultaneously possess excellent solar-blind ultraviolet light detection performance and electroluminescence performance. Based on this thin film material, multifunctional integrated devices combining photodetection and EL functions can be constructed, thereby improving the system's integration and compactness.

[0025] (4) High-performance solar-blind ultraviolet detector The Er-doped Ga₂O₃ thin-film device prepared in this invention achieves a high efficiency of 3.67 × 10⁻⁶ Ω·cm under a reverse bias voltage of -1 V and 254 nm ultraviolet light irradiation. 14 Jones's specific detection rate indicates that the device has extremely high sensitivity and can effectively detect weak solar-blind ultraviolet signals, meeting the urgent need for high-performance detectors in fields such as space communication and missile early warning. Attached Figure Description

[0026] The invention will be further described with reference to the accompanying drawings, but the contents of the drawings do not constitute any limitation on the invention.

[0027] Figure 1 This is a schematic diagram of the synthesis of doped thin films.

[0028] Figure 2 These are camera images of the PVA-Ga-Er organic precursor film and the prepared Ga2O3:Er film.

[0029] Figure 3 These are TEM test results for undoped Ga2O3 and Ga2O3:Er nanomaterials.

[0030] Figure 4 This is a schematic diagram of the construction steps for a heterojunction device.

[0031] Figure 5 These are local cross-sectional SEM images and EDS element distributions of the device.

[0032] Figure 6 These are the photoelectric performance test results and charge transfer mechanisms of devices (a)-(c).

[0033] Figure 7 These are the EL performance test results of the device.

[0034] Figure 8 (a) The device’s photo-electro-optical conversion performance and (a)-(c) visualization of ultraviolet signals.

[0035] Figure 9 The results show the effect of different amounts of liquid precursor on film thickness and roughness.

[0036] Figure 10 These are the (a) XRD and (b) EPR spectra of the materials at different Er doping concentrations.

[0037] Figure 11 The results are the calculated (a) valence band spectrum and (b) band gap of the material under different Er doping concentrations.

[0038] Figure 12 These are the photoelectric performance test results of the device under different Er doping concentrations.

[0039] Figure 13 These are the EL performance test results of the device under different Er doping concentrations.

[0040] Figure 14 These are the EL performance test results of devices with different rare earth dopants.

[0041] Figure 15These are the EL performance test results of devices with different shapes and rare earth dopants. Detailed Implementation

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0043] Example 1: Synthesis of 3 mol% Er-doped Ga₂O₃ (Ga₂O₃:Er) thin films. Specific procedures are as follows: Figure 1 As shown: (1) Gallium nitrate hydrate [Ga(NO3)3]. x [H2O, molecular weight: 255.74, Macklin, 0.5 g], erbium nitrate hydrate [Er(NO3)3·6H2O, molecular weight: 461.37, Macklin, 28 mg] powder, and 0.5 g of polyvinyl alcohol (PVA, model 2488: degree of polymerization 2400, degree of alcoholysis 88%) were added to a beaker containing 150 mL of deionized water. The doping concentration was defined as the ratio of Er / (Er+Ga), in mol%. The mixture was sonicated for 20 minutes to completely dissolve the Ga and Er precursor powders. The beaker was then sealed with aluminum foil and placed in an oven. The oven temperature was set to 80 °C and maintained for 60 minutes to completely dissolve the PVA particles in the water, at which point the solution contained a large number of bubbles. The beaker was removed from the oven and aged in a dry place for 8 hours to remove the bubbles, yielding a transparent liquid precursor.

[0044] (2) Titrate 15 mL of the obtained liquid precursor solution into a polystyrene culture dish. Place the culture dish containing the solution in an oven and dry at 80 °C for 5 hours to obtain a PVA-Ga-Er organic precursor membrane (approximately 13 μm thick). The PVA-Ga-Er organic precursor membrane can be peeled off from the polystyrene culture dish. Cut the PVA-Ga-Er organic precursor membrane into the required shape and store it in a dry environment for later use.

[0045] (3) Place the SiO2 / Si substrate with a 300 nm thick SiO2 layer on the heating stage. Transfer the cut PVA-Ga-Er organic precursor film onto the SiO2 / Si substrate. Set the target temperature of the heating stage to 100 °C and turn on the heating for 5 minutes. Due to the melting of PVA in the composite film, the organic precursor film can adhere to the substrate below during the heating process, thereby making the two tightly bonded.

[0046] (4) A SiO2 / Si substrate coated with PVA-Ga-Er is placed in the center of a quartz tube in a tube furnace. The quartz tube is opened at both ends during high-temperature heating. The substrate is annealed at 800 °C for 60 minutes in an air atmosphere to obtain a Ga2O3:Er thin film. During the heating process, PVA can react with oxygen to generate gas decomposition, and the precursors of Ga and Er are oxidized to form oxides, thereby forming Ga2O3:Er material.

[0047] Erbium nitrate hydrate was omitted in step (1), and the rest was the same as in Example 1, thus obtaining undoped Ga2O3 material.

[0048] Figure 2 Camera images of the PVA-Ga-Er organic precursor film and the corresponding Ga2O3:Er film. The PVA-Ga-Er film is pale yellow, while the prepared Ga2O3:Er film has a uniform and continuous color distribution on the SiO2 / Si substrate, with a size of up to 5 cm × 5 cm.

[0049] The effect of doping on the microstructure of the material was studied using transmission electron microscopy (TEM). Figure 3 a and Figure 3 Image b shows TEM images of undoped Ga2O3 and Ga2O3:Er nanomaterials obtained from thin films on SiO2 / Si substrates. Both synthesized films are composed of nanoparticles. Figure 3 c and Figure 3 In the image, d represents the corresponding local high-resolution TEM (HRTEM) image. No crystal features were observed in Ga2O3, while distinct lattice fringes (marked with yellow circles) were observed in Ga2O3:Er. Figure 3 In the magnified view of d, the atomic arrangement with an interplanar spacing of 0.252 nm corresponds to β -The (111) plane of Ga2O3. Meanwhile, the crystal characteristics of Ga2O3 and Ga2O3:Er can be revealed from the diffraction patterns, as shown below. Figure 3 China and Figure 3 As shown in Figure f, the diffraction patterns of Ga2O3 and Ga2O3:Er are divided into amorphous and polycrystalline states, respectively. The crystal planes (-201) and (111) in the diffraction rings of the latter are marked in the figure. TEM results confirm that Er doping can improve the crystallinity of Ga2O3.

[0050] Example 2: Construction and Performance of Heterojunction Devices The construction steps and conditions are basically the same as those for the synthesis of a single Ga2O3:Er thin film (Example 1), the difference being that a PVA (PVA-Ga-Zn) organic precursor film containing Ga and Zn precursors needs to be synthesized simultaneously, such as... Figure 4As shown, the precursors used in PVA-Ga-Zn are zinc sulfate (ZnSO4, molecular weight: 161.45, Macklin, 0.5 g) and Ga(NO3)3. x H₂O (0.038 g) and PVA (0.5 g), with Ga as the dopant for ZnO at a doping concentration of 5 mol%, were used to heat-treat PVA-Ga-Er (approximately 13 μm thick) and PVA-Ga-Zn (approximately 13 μm thick) organic precursor films at 110 °C for 5 minutes to obtain composite organic precursor films. These were cut to the desired shape and transferred to a SiO₂ / Si substrate with a SiO₂ thickness of 5 nm. The subsequent transfer and heat treatment process was consistent with that in Example 1 (first holding at 100 °C for 5 minutes, then annealing at 800 °C for 60 minutes in air). The substrate used for the device was p-type Si with a SiO₂ thickness of 5 nm. The resulting Ga-doped ZnO (GZO) served as the conductive film for the heterojunction device. Silver paste was coated onto the Si surface and dried at 140 °C for 1 hour to obtain an Ag metal back electrode (approximately 300 μm thick).

[0051] Figure 5 Figure a shows the structure of a multilayer heterojunction device built on a 5-nm-SiO2 / p-Si substrate. Figure 5 Image b shows a local cross-sectional scanning electron microscope (SEM) image and energy dispersive spectroscopy (EDS) elemental distribution of the device, confirming its multilayer structure.

[0052] Figure 6 In the figure, 'a' represents the power density of different 254 nm light sources. P Photocurrent-time of a device with a doping concentration of 3 mol% I ph -t )curve. Figure 6 b shows I ph -P The numerical dependence between the two can be described as follows: , (1) Fit index n A responsivity of approximately 0.89 indicates a complex recombination process within the electron transport channel. R ) and specific detectivity ( D* These are two key parameters for evaluating the performance of a photodetector, which can be obtained using the following formulas: , (2) , (3) in S and qThese are the effective area of ​​the device (~1 cm × 1 cm) and the elementary charge (1.6 × 10⁻⁶). -19 C), I dark Dark current (~6.4 × 10⁻⁶) -10 A). At a power density of 0.41 μW cm⁻¹ -2 hour, R and D* The values ​​reached their maximum values ​​of ~5.25 × 10⁻⁶. 3 mA W -1 and ~3.67 × 10 14 Jones. The device rise time (from 10% to 90%) and fall time (from 90% to 10%) obtained using an oscilloscope and a 254 nm pulsed light source were ~53 μs and ~52 μs, respectively. Figure 6 As shown in c. Figure 6 The diagram in section d illustrates the charge transfer mechanism of the heterojunction under illumination. E f This is the Fermi level. Under a reverse external electric field (E... ex Under 254 nm illumination, photoelectrons generated in p-Si move to the conduction band of Ga2O3:Er. E C ), while the valence band of Ga2O3:Er ( E V The remaining holes in the ) migrate to p-Si E V middle.

[0053] Subsequently, the EL performance of GZO / Ga2O3:Er / 5-nm-SiO2 / p-Si / Ag devices with the same structure was investigated. Figure 7 In the EL spectrum of a, the emission peaks located at ~409, 534, 550, and 658 nm correspond to Er, respectively. 3+ Ionic 2 H 9 / 2 → 4 I 15 / 2 , 2 H 11 / 2 → 4 I 15 / 2 , 4 S 3 / 2 → 4 I 15 / 2 and 4 F 9 / 2 → 4 I 15 / 2 Transition emission. The inset is a camera photograph of the device in a dark field, showing that its green light output is dominant. Figure 7Figure b shows the dependence of the EL spectrum on the device current, and the right-hand figure shows the emission peak intensity at 550 nm. I EL@550nm (Changes). I EL@550nm With current I The relationship can be described as , (4) The obtained index m The slope is approximately 1.44, indicating the presence of non-radiative centers that provide shunt paths for the current.

[0054] Meanwhile, the photoelectric detection and EL characteristics of the device can be used to realize the signal conversion from light to electricity to light. Figure 8 Figure a demonstrates the device under -18 V voltage and 254 nm light illumination with repeated switching. I and I EL@550nm The changes indicate that ultraviolet irradiation can cause synchronous changes in device current and EL intensity. This signal conversion behavior can be used to visualize solar-blind ultraviolet signals and provide timely feedback to monitor electric arcs in electronic devices, such as... Figure 8 As shown in b. Figure 8 Image c and image d in Figure 8 are dark-field camera images of the device under reverse bias voltage with and without an arc signal, respectively, indicating that the device can respond to an arc signal and generate visible light emission. Figure 8 The image shows the pulsed arc signal. I EL@550nm The changes indicate that the device has excellent stability and timely feedback capability, and also confirm that the constructed Ga2O3:Er-based device can realize photoelectric signal conversion.

[0055] Example 3: Effect of Liquid Precursor Dosage The synthesis steps and conditions are basically the same as those for the 3 mol% doped Ga2O3:Er thin film (Example 1), except that the amount of liquid precursor solution used in step (2) is different. The thickness of the PVA-Ga-Er composite film can be controlled by adjusting the volume of the precursor solution in the culture dish, thereby changing the thickness of the synthesized Ga2O3:Er film. Figure 9 Images a, b, c, and d are cross-sectional optical images of the PVA-Ga-Er composite film (top image), the optical image of the Ga2O3:Er film (middle image), and the corresponding atomic force microscopy (AFM) images of the Ga2O3:Er film (bottom image), respectively, with corresponding precursor solution volumes of 5 mL, 10 mL, 15 mL, and 20 mL. Figure 9The values ​​shown in the image are approximately 4 μm, 9 μm, 13 μm, and 18 μm. The arithmetic mean roughness of the thin film (…). R a The thickness is between 1.7 and 1.8 nm, indicating that the film thickness has no significant effect on its surface morphology. Figure 9 The thickness curve shown in Figure e confirms that the thickness of the Ga2O3:Er film ( δ G The thickness (μm) of PVA-Ga-Er can be changed by altering the thickness (μm). δ P The control is achieved by using μm. δ G and δ P Dependencies between them, such as Figure 9 As shown in f, it can be described by linear fitting as follows: , (5) This indicates that a 1 μm thick PVA-Ga-Er film can form an 11.4 nm Ga2O3:Er film.

[0056] This embodiment investigated the effect of liquid precursor dosage on film thickness and roughness. The results show that film thickness can be flexibly controlled by changing the liquid precursor dosage.

[0057] Example 4: Effect of Er doping concentration The synthesis steps and conditions were basically the same as those for the 3 mol% doped Ga2O3:Er thin film (Example 1), except that the amount of Er(NO3)3.6H2O used in step (1) was different. When the Er doping concentration was 1 mol%, 2 mol%, 3 mol%, and 4 mol%, the corresponding masses of Er(NO3)3.6H2O were ~9 mg, 19 mg, 28 mg, and 38 mg, respectively.

[0058] Figure 10 Figure 'a' shows the X-ray diffraction (XRD) patterns of films with different Er doping concentrations, where peaks marked with "*" correspond to the Si substrate. The undoped film is amorphous. With increasing doping concentration, the peaks at 30.5° and 32.2° become more pronounced, and their intensity continuously increases (marked with "Y"), corresponding to... β - The (-401) and (002) crystal planes of Ga2O3. Changes in XRD patterns indicate that Er doping can improve the crystallinity of Ga2O3. Further analysis of defect characteristics in different samples using electron paramagnetic resonance (EPR) spectroscopy was conducted. Figure 10(b) A characteristic peak at g≈2.004 was observed in the EPR spectra of all thin films, which is attributed to oxygen defects. Meanwhile, increasing Er doping concentration led to a decrease in EPR intensity, indicating a reduction in oxygen defects.

[0059] Subsequently, the band gap structure of the material was studied. Figure 11 In the diagram, 'a' represents the valence band spectrum of different samples. E f The distance between the valence band top and the Er doping concentration increases with increasing Er doping concentration. Figure 11 Figure b shows the absorption spectrum curves used to calculate the band gap. Er doping leads to a continuous decrease in the film band gap, which is beneficial for promoting the generation of photogenerated carriers. At doping concentrations of 0–4 mol%, the material band gap is 4.85–4.51 eV, where 0 mol% doping concentration represents the undoped state.

[0060] Figure 12 In the figure, 'a' represents the dark field current-voltage ratio of devices with different doping concentrations in a single logarithmic coordinate system. IV The current curves show that the current under negative voltage has been converted to a positive value. All devices exhibit excellent pn junction rectification characteristics. Meanwhile, with increasing Er doping concentration, the device current value continuously decreases in the reverse voltage region, which can be attributed to Er doping improving the Ga2O3 crystal quality and suppressing oxygen defects. Figure 12 Figure b shows different devices under a 254 nm light source and a -1 V bias voltage. I ph -t Curve. Increased Er doping concentration leads to I ph The doping concentration continued to increase, but the change was small at 3 mol% and 4 mol% doping concentrations. Furthermore, the photocurrent-to-dark-current ratio of the device at 3 mol% doping concentration (…) remained relatively stable. I light / I dark ) Reaching 1.1 × 10 4 .

[0061] Figure 13 Figures a and b in section 13 show the changes in the EL spectrum and characteristic emission peak intensity of the device at -0.9 mA, respectively, for devices with different doping concentrations. Unlike the photodetector performance, the EL performance of this device reaches its maximum at a doping concentration of 3 mol% at the same current. The decrease in EL intensity at 4 mol% can be attributed to the concentration quenching effect at higher doping concentrations.

[0062] This embodiment investigates the effect of Er doping concentration on material and device performance. Increasing Er doping concentration leads to a decrease in oxygen defect concentration and a reduction in the Ga2O3 bandgap, thereby improving the photodetector performance of the device. However, the optimal Er doping concentrations for photodetector and EL performance are different, at 4 mol% and 3 mol%, respectively.

[0063] Example 5: The effect of doped ions on EL performance The synthesis steps and conditions are basically the same as those for 3 mol% doped Ga2O3:Er thin films (Example 1), except that in step (1), Er(NO3)3.6H2O is adjusted to Eu(NO3)3.6H2O (Macklin, 28 mg) and Tm(NO3)3.6H2O (Macklin, 28 mg) to synthesize Ga2O3:Eu and Ga2O3:Tm thin films.

[0064] Figure 14 In Figures a and b, respectively, are the EL spectra of the GZO / Ga₂O₃:Eu / 5-nm-SiO₂ / p-Si / Ag and GZO / Ga₂O₃:Tm / 5-nm-SiO₂ / p-Si / Ag devices at -0.9 mA. Figure 14 In the middle a, the peaks at ~590 and 613 nm are respectively related to Eu 3+ Ionic 5 D0→ 7 F1 and 5 D0→ 7 F2 transition related; in Figure 14 In the middle b, the peaks at ~478 and 798 nm correspond to Tm, respectively. 3+ Ionic 1 G4→ 3 H6 and 1 G4→ 3 H5 transition emission. The dark-field camera image in the inset shows that the Eu and Tm-doped devices primarily output red and violet light, respectively.

[0065] This embodiment investigated the effect of doping ions on EL performance. As shown above, the EL spectrum and output color of the device can be flexibly controlled by changing the rare earth ions.

[0066] Example 6: The Influence of Organic Precursor Membrane Shape on EL The construction steps are basically the same as in Example 2, except that the shapes of the PVA-Ga-Er and PVA-Ga-Zn composite films were adjusted, and the universality of other rare earth ions was investigated. Since the shape of the GZO / Ga2O3:RE composite film is related to the precursor organic composite film, the EL pattern can be changed by cutting the shape of the organic composite film.

[0067] Figure 15 The diagram shows an EL test and dark-field camera images of devices with different shapes and doped ions, demonstrating that the EL output pattern of the device can be flexibly controlled.

[0068] This embodiment investigated the effect of organic precursor film shape on EL. As can be seen, this method has significant advantages in the personalized customization and design of light sources.

[0069] Although preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a rare earth-doped gallium oxide thin film, characterized by, The process is as follows: (1) adding deionized water to a mixture of a compound that can be dissolved in water and ionized to release RE 3+ , a compound that can be dissolved in water and ionized to release Ga 3+ , and PVA, and ultrasonically dissolving the mixture completely, sealing the solution, heating, and aging the heated solution at room temperature to obtain a liquid precursor; (2) The liquid precursor is dropped into a culture dish, dried, peeled off from the culture dish, and PVA-Ga-RE organic precursor film is obtained. The PVA-Ga-RE organic precursor film is cut into the required shape and placed in a dry environment for standby; (3) The PVA-Ga-RE organic precursor film is placed on the substrate and heated to make the organic precursor film adhere to the substrate; (4) The substrate covered with the PVA-Ga-RE organic precursor film is placed in a tubular furnace with open ends and heated at high temperature to obtain a Ga2O3 film.

2. The method of claim 1, wherein the method further comprises the step of: In step (1), the compound soluble in water and ionized to RE 3+ is at least one of the following: RE 3+ sulfate compound, chloride, acetate compound, nitrate compound; RE 3+ sulfate compound, chloride, acetate compound, or nitrate compound of Ga 3+ corresponding to the hydrate; the compound soluble in water and ionized to Ga is at least one of the following: nitrate, chloride, sulfate, citrate of gallium corresponding to the hydrate. ​ 3. The method of claim 1, wherein the gallium oxide thin film is doped with a rare earth element. In step (1), the PVA has an alcoholysis degree of (86-90)%, a polymerization degree of 1700-2500, a heating temperature of 80-95℃ after sealing for 30-90 minutes, and a solution aging time of 5-10 hours.

4. The method of claim 1, wherein the method further comprises the step of: In step (1), RE 3 + is at least one of Er 3+ , Eu 3+ and Tm 3+ , the RE 3+ doping concentration is 1 mol% to 4 mol% of the total mole amount of RE 3+ and Ga 3+ , and 0.4 to 0.6 g of PVA is required per 1 to 3 mmol of Ga 3+ . ​ 5. The method of claim 1, wherein the method further comprises the step of: In step (2), the liquid precursor is dried at a temperature of 70-98 ℃ for 4-8 hours. ​ 6. The method of claim 1, wherein the method further comprises the step of: In step (3), the substrate is a Si substrate, a Si substrate covered with SiO2, or a sapphire substrate; the heating temperature is 100-150 ℃, and the heating time is 3-10 minutes. ​ 7. The method of claim 1, wherein the method further comprises the step of: In step (4), the high-temperature heating temperature is 750-950 ℃, and the high-temperature heating time is 30-120 minutes. ​ 8. The rare earth-doped gallium oxide film obtained by the preparation method of any one of claims 1-7.

9. Use of a rare earth doped gallium oxide thin film in an optical integrated device, characterized in that, The process is as follows: S1, the PVA-Ga-Zn organic precursor film and the PVA-Ga-RE organic precursor film are prepared according to steps (1) and (2) of claim 1; S2, the PVA-Ga-RE organic precursor film and the PVA-Ga-Zn organic precursor film are bonded together by heat treatment to obtain a composite organic precursor film. The composite organic precursor film is placed on the substrate, and the PVA-Ga-RE organic precursor film is next to the substrate. The heating temperature is 100-150 ℃, and the heating time is 3-10 minutes; S3, the substrate covered with the composite organic precursor film is placed in a tubular furnace with open ends and heated at high temperature; S4, silver paste is coated on the other side of the substrate, dried at 130-150°C for 30-70 minutes, and an Ag metal back electrode is obtained.

10. Use according to claim 9, characterized in that, The doping amount of Ga in the PVA-Ga-Zn organic precursor film in S1 is 3 mol% to 6 mol% of the total amount of Ga and Zn, and 1 to 4 mmol of Zn per 1 mmol of Ga 2+ 0.4 to 0.6 g of PVA is required; the heat treatment in S2 refers to heating at 100 to 150 °C for 3 to 10 minutes; and the high-temperature heating temperature in S4 is 750 to 950 °C, and the high-temperature heating time is 30 to 120 minutes.

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