Cerium oxide doped indium oxide-based target material, method for preparing the same, and use thereof

Abstract

The application discloses a cerium oxide doped indium oxide based target material and a preparation method and application thereof, and comprises the following preparation raw materials in parts by weight: 97-99 parts of indium oxide, 1-3 parts of cerium oxide and 0.01-0.05 parts of metal oxide, wherein the metal oxide comprises at least one of aluminum oxide, zirconium oxide and titanium oxide. The application provides a cerium oxide doped indium oxide based target material and a preparation method and application thereof. The sintering density of the target material is improved by means of metal oxide doping, the pores between the grain boundaries are eliminated, and the bulk resistivity of the target material is significantly reduced. The application can be applied to magnetron sputtering film coating, and the mobility of the sputtered film is improved.

Description

Technical Field

[0001] This invention relates to the field of metal target technology, and in particular to a cerium oxide-doped indium oxide-based target, its preparation method, and its application. Background Technology

[0002] Currently, transparent conductive films are needed in the fields of photovoltaic cells, liquid crystal displays, and LED optoelectronic devices. In heterojunction cells, perovskite cells, and their stacked technologies, due to the poor lateral conductivity of microcrystalline silicon films, TCO films are often deposited on both sides using PVD (sputtering deposition) for light transmission and current transport. Commonly used transparent conductive film materials are ITO (indium oxycarbonate), despite ITO having a high optical transmittance of up to 80% and a low resistivity of 7x10⁻⁶ in the visible light wavelength range. -4 While ITO films exhibit high transmittance (Ω·cm), in the near-infrared band, parasitic absorption of photons generates free carriers, leading to reduced film transmittance. This results in decreased photon energy absorption and reduced power generation efficiency. Furthermore, maintaining high transmittance in ITO films compromises sheet resistance, limiting their application in large-area batteries and touch displays. Compared to ITO transparent conductive films, ICO films offer a better match in optical transmittance and conductivity. In solar photovoltaic applications, ICO transparent conductive films can achieve an electron mobility of 130–145 cm⁻¹. 2 V -1 s -1 ICO (Inductively Coupled Electron) is expected to replace ITO in heterojunction solar cells, perovskite solar cells, and their tandem solar cells. ICO materials have been developed as a high-performance transparent conductive film material in the photovoltaic industry, leveraging their high transparency and conductivity to replace traditional ITO transparent conductive films. The main methods for preparing ICO thin film materials are reactive plasma deposition (RPD) and photovoltaic sputtering (PVD). ICO films prepared by RPD show significant efficiency improvements in heterojunction solar cells, with a gain of approximately 0.35-0.6%, but RPD equipment has poor stability and a short maintenance cycle, preventing its mass production for now. PVD sputtering generally uses a DC magnetron sputtering power supply, which is simple, reliable, stable, powerful, and has a fast deposition rate. The target material is placed in an electric field loop and bombarded by Ar ions under magnetic field discharge, sputtering the desired material onto the substrate. Therefore, the target material itself needs to have high density and low bulk resistivity. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a cerium oxide-doped indium oxide-based target, its preparation method, and its application. This invention improves the sintering density of the target material, eliminates porosity between grain boundaries, and significantly reduces the bulk resistivity of the target material through metal oxide doping. It can be applied to magnetron sputtering coating to improve the mobility of sputtered thin films.

[0004] The first aspect of the present invention provides a cerium oxide-doped indium oxide-based target material, which, by weight, comprises the following raw materials: 97-99 parts indium oxide, 1-3 parts cerium oxide, and 0.01-0.05 parts metal oxide.

[0005] The metal oxide includes at least one of aluminum oxide, zirconium oxide, and titanium oxide.

[0006] This invention provides a cerium oxide-doped indium oxide-based target material, the raw material composition of which, by weight, comprises: 97-99 parts indium oxide, 1-3 parts cerium oxide, and 0.01-0.05 parts metal oxide, wherein the metal oxide is selected from at least one of alumina, zirconium oxide, and titanium oxide. This specific composition design, through multiple synergistic effects, achieves a significant improvement in target material performance, and has the following outstanding beneficial effects:

[0007] First, this invention fully utilizes the cerium oxide doping ratio (1 to 3 parts) by precisely controlling the doping ratio of cerium oxide. 4+ With In 3+ With similar ionic radius characteristics, Ce... 4+ It can effectively dissolve into the In2O3 lattice, replacing part of the In. 3+ The above composition significantly increases the free electron concentration, resulting in excellent conductivity of the target material. This ensures sufficient oxygen vacancy concentration while avoiding lattice distortion caused by excessive doping. Secondly, in terms of microstructure control, the introduction of trace metal oxides (0.01–0.05 parts) exhibits a significant synergistic effect in subsequent preparation processes: zirconium oxide can form a diffusion barrier at grain boundaries, effectively suppressing the volatilization loss of In2O3 at high temperatures; alumina restricts grain boundary migration through pinning effect, controlling the grain size within the optimized range of 1–3 μm; and titanium oxide forms a liquid phase during sintering, promoting particle rearrangement and densification.

[0008] According to some embodiments of the present invention, the BET of the metal oxide is 10–25 m. 2 / g, D50≤2μm, Dmax≤10μm.

[0009] The specific surface area (BET) of the metal oxide described in this invention is controlled between 10 and 25 m². 2 / g, with a particle size distribution satisfying D50≤2μm and Dmax≤10μm, this specific physical parameter design significantly improves the overall performance of the target material through the following mechanism:

[0010] 10~25m 2The specific surface area range of / g ensures that the metal oxide has moderate surface activity and provides sufficient surface energy, which is beneficial for full contact and dispersion with other components during ball milling. At the same time, it avoids the problem of particle agglomeration caused by excessive surface energy, so that trace metal oxides can be uniformly distributed in the indium cerium oxide matrix. The submicron-level main particle size (D50) ensures the particle size matching between the metal oxide and the matrix material, avoiding component segregation due to size differences. Meanwhile, the fine particle size reduces the diffusion distance of the material and promotes the mass transfer process during sintering.

[0011] According to some embodiments of the present invention, the raw materials for preparing the cerium oxide-doped indium oxide-based target further include a dispersant; the dispersant includes polyvinylpyrrolidone.

[0012] A second aspect of the present invention provides a method for preparing a cerium oxide-doped indium oxide-based target, comprising the following steps:

[0013] S1. After mixing the indium oxide and the cerium oxide to obtain a slurry, the slurry is dispersed by sand milling and then post-processed to obtain an indium oxide cerium powder precursor.

[0014] S2. Heat-treat the indium cerium oxide powder precursor to obtain cerium-doped indium oxide powder;

[0015] S3. The cerium-doped indium oxide powder and the metal oxide powder are mixed, granulated, and dried to obtain a mixed granulated powder.

[0016] S4. After the mixed granulated powder is shaped, it is degreased and sintered to obtain cerium-doped indium oxide target material.

[0017] According to some embodiments of the present invention, in step S1, the sand milling and dispersion step includes: transferring the slurry into a sand mill containing zirconium beads for sand milling at a speed of 1400-2000 rpm for a sand milling time of 2-5 hours.

[0018] According to some embodiments of the present invention, in step S2, the heat treatment step includes: calcination; the parameters of the calcination include: heating to 300°C at a rate of 0.5°C / min and holding for 1-2 hours, heating to 500°C at a rate of 1°C / min and holding for 1-2 hours, then heating to 800°C at a rate of 0.5-1°C / min and holding for 1-2 hours, heating to 900°C at a rate of 1°C / min and holding for 1-2 hours, and cooling to 100°C at a rate of 1-2°C / min.

[0019] According to some embodiments of the present invention, in step S4, the molding includes warm pressure isostatic pressing; the molding pressure of the warm pressure isostatic pressing is 150MPa to 250MPa.

[0020] According to some embodiments of the present invention, in step S4, the degreasing temperature is 600-650°C, and the degreasing holding time is 2-4 hours.

[0021] According to some embodiments of the present invention, in step S4, the sintering step includes: heating to 900-950°C at a heating rate of 1°C / min, holding at that temperature for 2-20 hours in an oxygen system; heating to 1400-1450°C at a heating rate of 0.5°C / min, holding at that temperature for 2-6 hours; heating to 1450-1500°C at a heating rate of 0.3°C / min, holding at that temperature for 10-12 hours; heating to 1500°C-1600°C at a heating rate of 0.1-0.3°C / min, holding at that temperature for 12-14 hours; then cooling to 950-1000°C at a heating rate of 1°C / min, stopping the gas supply, and cooling to room temperature at a heating rate of 1°C / min.

[0022] A sand milling process was used to process the mixed slurry of indium oxide and cerium oxide, combined with ultrasonic-assisted drying technology to ensure the acquisition of uniform precursor powder. Mechanochemical action effectively broke up the hard agglomerates of raw material particles, laying the foundation for the subsequent uniform solid solution of Ce. Compared with traditional mechanical mixing, sand milling improved the uniformity of Ce distribution by approximately 40% and significantly reduced the residual amount of the second-phase CeO2.

[0023] In step S2, a multi-stage heating program is designed (300℃ / 1-2h→500℃ / 1-2h→800℃ / 1-2h→900℃ / 1-2h), and Ce is achieved by controlling the crystal phase transformation kinetics. 4+ The process involves a gradual solid solution treatment. The low-temperature stage (300-500℃) primarily removes residual organic matter; the medium-temperature stage (500-800℃) initiates the initial solid solution reaction; and the high-temperature stage (800-900℃) completes the deep doping of Ce. This process stabilizes the final powder specific surface area at 7-15 m². 2 / g, BET test showed that the density of active sites increased by 25% compared with conventional calcination.

[0024] In step S4, a "segmented oxygen atmosphere control" strategy is adopted: high-flow-rate oxygen is introduced at 900-950℃ to promote complete decomposition of organic matter; densification dominated by grain boundary diffusion is achieved in the high-temperature range of 1400-1500℃ through precise heating rate control (0.3-0.5℃ / min); finally, the target material is held at 1500-1600℃ for 12-14 hours to reduce its resistivity.

[0025] A third aspect of the present invention provides an application of the cerium oxide-doped indium oxide-based target in reflective films, transparent conductive films, and organic light-emitting diodes.

[0026] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0027] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0029] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0030] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0031] Example 1

[0032] This embodiment provides a cerium oxide-doped indium oxide-based target and its preparation method, specifically:

[0033] The preparation method of cerium oxide-doped indium oxide-based target material includes the following steps:

[0034] S1. Dissolve indium in an alcohol solution, hydrolyze and calcine, then spray dry to obtain indium oxide powder; purchase cerium oxide powder with a purity ≥99.999% and a particle size ≤0.1μm; mix cerium oxide powder and indium oxide powder at an atomic ratio of In:Ce = 99:1; add pure water and 0.3% by mass of dispersant, and stir to obtain a mixed slurry;

[0035] Sand milling: The slurry is transferred into a sand mill containing Φ0.50mm zirconium beads for sand milling at a speed of 1400-2000rpm for 2 hours. The sand-milled slurry is then heated and baked while being subjected to ultrasonic vibration until it is dried. Finally, it is pulverized to obtain the powder precursor.

[0036] S2. The powder precursor is subjected to high-temperature calcination. During the calcination process, the temperature is increased to 300℃ at a rate of 0.5℃ / min and held for 1 hour, then increased to 500℃ at a rate of 1℃ / min and held for 1 hour, then increased to 800℃ at a rate of 0.5℃ / min and held for 1 hour, then increased to 900℃ at a rate of 1℃ / min and held for 1 hour, and finally decreased to 100℃ at a rate of 1℃ / min to obtain indium cerium oxide powder, i.e., cerium-doped indium oxide powder, with a purity ≥99.99% and a powder BET of 7-15m. 2 Between / g, D50≤2μm, Dmax≤40μm;

[0037] S3. Other doped oxide powders should be purchased externally, with a purity ≥99.99% and a BET value of 10-25 μm. 2 The cerium-doped indium oxide powder was prepared with a density between 1 / g and 2μm, D50 ≤ 2μm, and Dmax ≤ 10μm. It was then mixed with metal oxide powder at a mass ratio of 1-x:x (where x = 0.1%) in a deionized aqueous solvent with a dispersant added. The mixture was ball-milled, first with 0.60mm zirconium beads at 600 rpm for 8 hours, then with 0.30mm zirconium beads at 800 rpm for 8 hours. A binder (PVA) and a plasticizer (PEG) were added, followed by stirring and filtration. The binder accounted for 0.4% of the total mass of the metal oxide component, and the plasticizer accounted for 0.1%. The mixture was then granulated by spray drying to obtain a mixed granulated powder. The specific surface area of ​​the powder was measured to be within 5m². 2 / g to 15m 2 The density is between 1.00 g / cm³, D50 ≤ 100 nm, and Dmax ≤ 4 μm. 3 -1.60g / cm 3 Between these ranges, the moisture content is ≤1%.

[0038] S4. Using a rotating target mold, inject powder into the mold. Increase the compaction density of the powder by mechanically vibrating the mold at a frequency of 20-50Hz. After sealing the mold, use WCIP molding. After isostatic pressing, obtain the target blank and then perform degreasing treatment at 600℃ for 2 hours. After degreasing, raise the temperature to 900℃ at a rate of 1℃ / min, introduce oxygen at a flow rate of 30L / min, and hold for 2 hours. After holding, raise the temperature to 1400℃ at a rate of 0.5℃ / min for 2-6 hours. After holding, raise the temperature to 1450℃ at a rate of 0.3℃ / min for 10 hours. After holding, raise the temperature to the maximum temperature at a rate of 0.1℃ / min for 12 hours, with the maximum temperature being 1500℃. After the heat treatment was completed, the temperature was lowered to 950℃ at a rate of 1℃ / min, then the gas flow was stopped, and the temperature was lowered to room temperature at a rate of 1℃ / min to obtain a cerium-doped indium oxide target. The target density was measured by Archimedes' displacement method, and the density reached 7.11 g / cm³. 3 ;

[0039] S5. Place the sintered target cylinder into a lathe for grinding. Use an 800-grit grinding wheel for rough grinding for 8 hours, and use a 400-grit grinding wheel for fine grinding for 8 hours.

[0040] S6. The processed cerium-doped indium oxide-based target material was measured. The target density was tested using the Archimedes water displacement method, the resistivity of the target material was tested using a resistivity meter, the grain size was observed using a metallographic microscope, and the uniformity of Ce element distribution in the target material was detected using EDS. The specific parameters and test results are shown in Table 1. The balance is indium oxide.

[0041] Examples 2-5

[0042] Examples 2-5 provide a cerium oxide-doped indium oxide-based target and its preparation method. The difference between Examples 2-5 and Example 1 is that the specific components are different, as shown in Table 1, while the other conditions are the same.

[0043] Comparative Examples 1-3

[0044] Comparative Examples 1 and 2 provide a cerium oxide-doped indium oxide-based target and its preparation method. The difference between Comparative Examples 1 and 2 and Example 1 is that the specific components are different, as shown in Table 1, while the other conditions are the same.

[0045] Table 1. Performance Testing

[0046]

[0047] Examples 1-7 have adjusted the doping composition and ratio compared to Comparative Examples 1-3, wherein the mass ratio of indium oxide is 96-99%, the mass ratio of cerium oxide is 1-3%, and the mass ratio of trace metal oxides (alumina, zirconium oxide, titanium oxide) is 0.02-0.2%.

[0048] Cerium oxide, as a rare earth oxide, has a coordination number of 6. 4+ The effective ionic radius (0.101 nm) is close to that of In with the same coordination number. 3+ (0.094nm), therefore, cerium ions doped with cerium oxide are relatively easy to insert into the indium oxide lattice and replace indium ions. At high temperatures, the unique reactivity of rare earth elements, the instability of their outer electrons, and their tendency to leak out in large quantities cause nearby oxygen atoms to detach during the substitution of indium ions, forming oxygen vacancies and promoting the growth of the indium oxide lattice. This also generates a large number of electrons, greatly increasing the conductivity of the sintered body. However, Ce... 4+ The effective ionic radius is greater than that of In 3+ Excessive doping can hinder lattice growth and cause lattice distortion, so the amount of cerium oxide doping must be controlled.

[0049] By using trace amounts of oxides (zirconia, alumina, titanium dioxide, etc.) to assist in the sintering of indium oxide-based targets, the volatilization of indium oxide at high temperatures is suppressed, the precipitation of cerium oxide grains is suppressed, internal porosity is reduced, and grain size of about 1-3 μm is obtained, which promotes sintering densification.

[0050] Comparative Example 1 (without metal oxides): The lack of alumina / zirconium / titanium to aid sintering and the grain boundary pinning effect resulted in insufficient sintering densification and more pores, thus leading to poor density and electrical conductivity.

[0051] In Comparative Example 2, the excessive addition of (0.2% metal oxide) disrupted the integrity of the indium oxide lattice, forming too many high-resistivity grain boundary phases, which in turn hindered conductivity and reduced density.

[0052] Comparative Example 3 showed that excessive metal oxidation led to a significant increase in resistivity and a loose structure.

[0053] Examples 1-6 demonstrate how the production of indium cerium oxide powder and the precise control of the doping amount of trace oxides result in sintered targets with excellent properties such as high density and low bulk resistivity. EDS analysis of the uniformity of Ce element distribution in the target shows a uniformity of approximately 1% deviation. The processed targets can be stably used for magnetron sputtering (PVD) coating.

[0054] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A cerium oxide-doped indium oxide-based target, characterized in that, The preparation materials, by weight, include the following: 97-99 parts indium oxide, 1-3 parts cerium oxide, and 0.01-0.05 parts metal oxide; The metal oxide includes at least one of aluminum oxide, zirconium oxide, and titanium oxide; The BET of the metal oxide is 10~25m. 2 / g, D50≤2μm, Dmax≤10μm; The cerium oxide-doped indium oxide-based target is prepared by a method comprising the following steps: S1. After mixing the indium oxide and the cerium oxide to obtain a slurry, the slurry is dispersed by sand milling and then post-processed to obtain an indium oxide cerium powder precursor. S2. Heat-treat the indium cerium oxide powder precursor to obtain cerium-doped indium oxide powder; S3. The cerium-doped indium oxide powder and the metal oxide powder are mixed, granulated, and dried to obtain a mixed granulated powder. S4. After the mixed granulated powder is shaped, it is degreased and sintered to obtain a cerium-doped indium oxide target. In step S2, the heat treatment step includes calcination; the parameters of the calcination include: heating to 300°C at a rate of 0.5°C / min and holding for 1-2 hours, heating to 500°C at a rate of 1°C / min and holding for 1-2 hours, heating to 800°C at a rate of 0.5-1°C / min and holding for 1-2 hours, heating to 900°C at a rate of 1°C / min and holding for 1-2 hours, and cooling to 100°C at a rate of 1-2°C / min.

2. The cerium oxide-doped indium oxide-based target according to claim 1, characterized in that, The raw materials for preparing the cerium oxide-doped indium oxide-based target also include a dispersant; the dispersant includes polyvinylpyrrolidone.

3. The cerium oxide-doped indium oxide-based target according to claim 1, characterized in that, In step S1, the sand milling and dispersion step includes: transferring the slurry into a sand mill containing zirconium beads for sand milling at a speed of 1400-2000 rpm for 2-5 hours.

4. The cerium oxide-doped indium oxide-based target according to claim 1, characterized in that, In step S4, the molding includes warm pressure isostatic pressing; the molding pressure of the warm pressure isostatic pressing is 150MPa~250MPa.

5. The cerium oxide-doped indium oxide-based target according to claim 1, characterized in that, In step S4, the degreasing temperature is 600-650℃, and the degreasing holding time is 2-4 hours.

6. The cerium oxide-doped indium oxide-based target according to claim 1, characterized in that, In step S4, the sintering step includes: heating to 900-950℃ at a heating rate of 1℃ / min, holding at that temperature for 2-20h in an oxygen system; heating to 1400-1450℃ at a heating rate of 0.5℃ / min, holding at that temperature for 2-6h; heating to 1450-1500℃ at a heating rate of 0.3℃ / min, holding at that temperature for 10-12h; heating to 1500℃-1600℃ at a heating rate of 0.1-0.3℃ / min, holding at that temperature for 12-14h; then cooling to 950-1000℃ at a heating rate of 1℃ / min, stopping the gas supply, and cooling to room temperature at a heating rate of 1℃ / min.

7. The application of the cerium oxide-doped indium oxide-based target as described in claim 1 in transparent conductive films for displays and photovoltaic cells, and organic light-emitting diodes.

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