AZO target material with good photoelectric property and preparation process thereof

Abstract

The invention discloses an AZO target material with good photoelectric performance. The AZO target material is prepared from a base material, a doping agent and a sintering aid according to the mass percent of 96%-98%: 1.5%-3%: 0.1%-0.5%. A preparation process comprises the steps of 1, raw material pretreatment, 2, primary calcination treatment, 3, forming treatment, 4, sintering treatment and 5, precision machining. By adding the sintering aid, a liquid phase layer can be formed during sintering, the grain boundary oxygen vacancy concentration is effectively reduced, the resistivity is reduced, and the visible light transmittance is improved; by means of the method of two times of sintering treatment, volatilization loss of zinc can be reduced, a nanoscale powder structure is matched with SPS rapid sintering heat preservation, abnormal growth of crystal grains is restrained, uniformity of the crystal grain size is effectively guaranteed, meanwhile, the nanoscale powder can improve sintering activity and reduce sintering cost, and the method is suitable for batch production.

Description

Technical Field

[0001] The present invention relates to the technical field of functional ceramic materials, and in particular to an AZO target material with good photoelectric properties and a preparation process thereof. Background Art

[0002] AZO target (zinc oxide aluminum ceramic target) is a composite material with zinc oxide (ZnO) and aluminum oxide (Al2O3) as the main components. Its core characteristic is to improve conductivity and transmittance through doping modification, and it is widely used in the field of thin film deposition.

[0003] The current preparation of AZO targets mainly adopts solid phase sintering, sol-gel method, spray pyrolysis method or vapor deposition method. Among them, solid phase sintering is simple in process and low in cost, and is the main technology for industrial preparation of AZO targets. However, the sintering temperature of solid phase sintering is high and the sintering time is long, which can easily lead to coarsening of ZnO crystals, reduce the density of target materials, and affect the uniformity of thin films. At the same time, the Al content in the material is high. 3+ It is easy to cause lattice distortion. Excessive Al content or uneven distribution will lead to an imbalance between carrier concentration and mobility, limiting the optimization of photoelectric performance. In addition, traditional processes are difficult to suppress the aggregation of oxygen vacancies, resulting in large fluctuations in target resistivity and reduced visible light transmittance. Therefore, the present invention proposes an AZO target material with good photoelectric performance and its preparation process to solve the problems existing in the prior art. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to propose an AZO target material with good photoelectric properties and a preparation process thereof. The AZO target material with good photoelectric properties and its preparation process can form a liquid phase layer during sintering by adding a sintering aid, effectively reducing the concentration of oxygen vacancies at the grain boundaries, reducing the resistivity and improving the visible light transmittance; the double sintering treatment method can reduce the volatilization loss of zinc, and the nano-scale powder structure and the SPS rapid sintering and heat preservation can inhibit the abnormal growth of grains and effectively ensure the uniformity of grain size. At the same time, the nano-scale powder can improve the sintering activity, reduce the sintering cost, and is suitable for mass production.

[0005] To achieve the purpose of the present invention, the present invention is implemented through the following technical solution: an AZO target material with good photoelectric properties, including a base material, a dopant and a sintering aid in a mass percentage of 96%-98%:1.5%-3%:0.1%-0.5%, wherein the base material is high-purity ZnO, the dopant is Al2O3, and the sintering aid is a Bi2O3-Y2O3 composite aid, wherein the molar ratio of Bi2O3 to Y2O3 is 2-4:1.

[0006] A further improvement is that the resistivity of the target material is ≤9.6×10 -5Ω·cm, average visible light transmittance ≥88%, carrier concentration 10 20 -10 21 cm -3 , carrier mobility ≥15cm 2 / V·s.

[0007] A process for preparing an AZO target material with good photoelectric performance comprises the following steps:

[0008] Step 1: Pre-treating the raw materials: weighing the zinc source powder, aluminum source powder and sintering aid according to the mass percentage, adding anhydrous ethanol as a dispersion medium and wet grinding to obtain a uniformly dispersed mixed slurry;

[0009] Step 2: Primary calcination treatment: the mixed slurry is dried by rotary evaporation at 80-100°C, ground and passed through a 200-mesh sieve to obtain a nano-scale mixed powder with good fluidity, and the mixed powder is placed in a microwave oven for two-stage calcination to obtain a nano-powder;

[0010] Step 3: Molding: inject the nanopowder into a rubber mold, apply a pressure of 100-200 MPa in a cold isostatic press and hold the pressure for 5-10 minutes to obtain a cylindrical body;

[0011] Step 4: Sintering treatment: Place the green body into a graphite mold and place it in an SPS furnace. Heat it to 1100-1200°C at a rate of 100-200°C / min and hot press it under an axial pressure of 20-50 MPa for 1-2 hours. Then heat it to 1200-1400°C and sinter it in two stages and keep it at this temperature for 2-3 hours to obtain a cylindrical target.

[0012] Step 5: Precision machining: The sintered cylindrical target is cut with diamond wire and the surface is ground and polished to a roughness Ra ≤ 0.1 μm and a flatness error ≤ ± 0.05 mm to obtain the AZO target.

[0013] A further improvement is that in step 1, the zinc source powder is ZnO powder with a particle size of ≤50nm and a purity of ≥99.99%, the aluminum source powder is Al2O3 powder with a particle size of ≤30nm, and the sintering aid is a composite powder of Bi2O3 and Y2O3 with a particle size of ≤50nm.

[0014] A further improvement is that: the wet grinding in step 1 uses zirconia balls, the ball-to-material ratio is 10:1, the rotation speed is 80-120 rpm, and the ball milling time is 6-12 hours.

[0015] A further improvement is that the volume ratio of the dispersion medium anhydrous ethanol to the mixture of the zinc source powder, the aluminum source powder and the sintering aid is 1:3.

[0016] A further improvement is that the microwave calcination in step 2 is carried out in an atmosphere of Ar:O2=9:1, the first stage is kept warm at 390-410°C for 1 hour, and the second stage is kept warm at 590-610°C for 1 hour.

[0017] A further improvement is that: in step 4, after the second stage sintering, the heat is kept under a vacuum degree of ≤5Pa.

[0018] The beneficial effects of the present invention are as follows: by adding a sintering aid, a liquid phase layer can be formed during sintering, which effectively reduces the concentration of oxygen vacancies at the grain boundaries, reduces the resistivity, and improves the visible light transmittance;

[0019] The preparation method reduces the volatilization loss of zinc through two sintering treatments. The nano-scale powder structure and SPS rapid sintering and heat preservation inhibit abnormal grain growth and effectively ensure the uniformity of grain size. At the same time, the nano-scale powder can improve the sintering activity and reduce the sintering cost, making it suitable for mass production. The prepared target material has a uniform microstructure, high density, and stable optoelectronic properties, which is of great significance for promoting the application of TCO materials in the optoelectronics field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0021] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0022] Transparent conductive oxide (TCO) films have become one of the core materials for optoelectronic devices due to their high visible light transmittance, low resistivity, and good chemical stability. Among them, aluminum-doped zinc oxide (AZO, ZnO:Al) has abundant raw materials (ZnO reserves are more than 1000 times that of In2O3), low cost, non-toxicity, and excellent optoelectronic properties (theoretical carrier mobility can reach 100cm 2 / V·s and above), it is one of the most promising TCO materials.

[0023] Currently, the preparation technologies of AZO targets mainly include solid-phase sintering, sol-gel, spray pyrolysis, and vapor deposition. Among them, solid-phase sintering is the mainstream technology for industrial preparation of AZO targets due to its simple process and low cost. However, the traditional solid-phase sintering method has the following key problems:

[0024] First, the solid-phase sintering method usually has a sintering temperature of >1500°C and a sintering time of 10-20 hours. The high temperature and long sintering time can easily lead to coarsening of ZnO crystals, with a particle size >10μm, resulting in a target relative density of <95%, reducing the density of the target and affecting the uniformity of the film.

[0025] Secondly, the Al in the material 3+ It is easy to cause lattice distortion. Excessive Al content (>3at%) or uneven distribution will lead to an imbalance between carrier concentration and mobility. For example, scattering is enhanced at high concentrations, mobility decreases, and the optimization of optoelectronic performance is limited.

[0026] At the same time, traditional processes are difficult to suppress the aggregation of oxygen vacancies, resulting in large fluctuations in the resistivity of the target material, visible light transmittance of less than 85%, and reduced transmittance.

[0027] Therefore, the development of an AZO target material with uniform microstructure, high density, and stable photoelectric performance and its efficient preparation method are of great significance to promoting the application of TCO materials in the field of optoelectronics.

[0028] Example 1

[0029] This embodiment provides an AZO target with good photoelectric properties, comprising a base material, a dopant, and a sintering aid in a ratio of 97%:2.5%:0.5% by mass, wherein the base material is high-purity ZnO, the dopant is Al2O3, and the sintering aid is a Bi2O3-Y2O3 composite aid, wherein the molar ratio of Bi2O3 to Y2O3 is 4:1;

[0030] according to Figure 1 As shown, the preparation process includes the following steps:

[0031] Step 1: Pre-treating the raw materials: weighing ZnO powder with a particle size of ≤50 nm and a purity of ≥99.99%, Al2O3 powder with a particle size of ≤30 nm, and a composite powder of Bi2O3 and Y2O3 with a particle size of ≤50 nm in a mass percentage of 97%:2.5%:0.5% to obtain a mixture, and adding anhydrous ethanol as a dispersion medium in a volume ratio of anhydrous ethanol to the mixture of 1:3 to obtain a uniformly dispersed mixed slurry;

[0032] Zirconia balls were used for wet grinding, with a ball-to-material ratio of 10:1, a rotation speed of 100 rpm, and a ball milling time of 8 h.

[0033] Step 2: Primary calcination treatment: the mixed slurry is dried by rotary evaporation at 100°C, ground and passed through a 200-mesh sieve to obtain a nano-scale mixed powder with good fluidity, and the mixed powder is placed in a microwave oven for two-stage calcination to obtain a nano-powder;

[0034] The microwave calcination was carried out in an atmosphere of Ar:O2=9:1 (volume ratio, the same below), with the first stage being kept at 410°C for 1 hour, and the second stage being kept at 600°C for 1 hour.

[0035] Step 3: Molding: inject the nanopowder into a rubber mold, apply a pressure of 150 MPa in a cold isostatic press and hold the pressure for 8 minutes to obtain a cylindrical body;

[0036] Step 4: Sintering treatment: Place the green body into a graphite mold and place it in an SPS furnace. Heat it to 1100°C at a rate of 150°C / min and hot press it under an axial pressure of 30 MPa for 1 hour. Then heat it to 1300°C for two-stage sintering and keep it at a vacuum of 5 Pa for 2 hours to obtain a cylindrical target.

[0037] Step 5: Precision machining: The sintered cylindrical target is cut with diamond wire and the surface is ground and polished to a roughness Ra ≤ 0.1 μm and a flatness error ≤ ± 0.05 mm to obtain the AZO target.

[0038] The AZO target prepared in this example was tested for performance and the resistivity was found to be 9.2×10 -5 Ω·cm, the average visible light transmittance is 89.5%, and the carrier concentration is 1.8×10 21 cm -3 , carrier mobility 16.5cm 2 / V·s, and its relative density is 98.2%.

[0039] Example 2

[0040] This embodiment provides a preparation process of an AZO target material with good photoelectric performance, comprising the following steps:

[0041] Step 1: Pre-treating the raw materials: weighing ZnO powder with a particle size of ≤50 nm and a purity of ≥99.99%, Al2O3 powder with a particle size of ≤30 nm, and a composite powder of Bi2O3 and Y2O3 with a particle size of ≤50 nm in a mass percentage of 97.5%:2.2%:0.3% to obtain a mixture, and adding anhydrous ethanol as a dispersion medium in a volume ratio of anhydrous ethanol to the mixture of 1:3 to obtain a uniformly dispersed mixed slurry;

[0042] Zirconia balls were used for wet grinding, with a ball-to-material ratio of 10:1, a rotation speed of 100 rpm, and a ball milling time of 8 h.

[0043] Step 2: Primary calcination treatment: the mixed slurry is dried by rotary evaporation at 100°C, ground and passed through a 200-mesh sieve to obtain a nano-scale mixed powder with good fluidity, and the mixed powder is placed in a microwave oven for two-stage calcination to obtain a nano-powder;

[0044] The microwave calcination was carried out in an atmosphere of Ar:O2=9:1, with the first stage being kept at 410°C for 1 hour and the second stage being kept at 600°C for 1 hour.

[0045] Step 3: Molding: inject the nanopowder into a rubber mold, apply a pressure of 150 MPa in a cold isostatic press and hold the pressure for 8 minutes to obtain a cylindrical body;

[0046] Step 4: Sintering treatment: Place the green body into a graphite mold and place it in an SPS furnace. Heat it to 1100°C at a rate of 150°C / min and hot press it for 1 hour under an axial pressure of 30 MPa. Then heat it to 1300°C for two-stage sintering and keep it warm for 2 hours under a vacuum of 5 Pa to obtain a cylindrical target.

[0047] Step 5: Precision machining: The sintered cylindrical target is cut with diamond wire and the surface is ground and polished to a roughness Ra ≤ 0.1 μm and a flatness error ≤ ± 0.05 mm to obtain the AZO target.

[0048] The performance test shows that the resistivity of the AZO target prepared in this example is 9.6×10 -5 Ω·cm, the average visible light transmittance is 90.1%, and the carrier concentration is 1.6×10 21 cm -3 , carrier mobility 16.7cm 2 / V·s, and its relative density is 99.3%.

[0049] Comparative Example 1

[0050] This embodiment provides a preparation process of an AZO target material with good photoelectric performance, comprising the following steps:

[0051] Step 1: Pre-treating the raw materials: weighing ZnO powder with a particle size of ≤50 nm and a purity of ≥99.99% and Al2O3 powder with a particle size of ≤30 nm in a mass ratio of 97%:3% to obtain a mixture, and adding anhydrous ethanol as a dispersion medium in a volume ratio of anhydrous ethanol to the mixture of 1:3 to obtain a uniformly dispersed mixed slurry;

[0052] Zirconia balls were used for wet grinding, with a ball-to-material ratio of 10:1, a rotation speed of 100 rpm, and a ball milling time of 8 h.

[0053] Step 2: Primary calcination treatment: the mixed slurry is dried by rotary evaporation at 100°C, ground and passed through a 200-mesh sieve to obtain a nano-scale mixed powder with good fluidity, and the mixed powder is placed in a microwave oven for two-stage calcination to obtain a nano-powder;

[0054] The microwave calcination was carried out in an atmosphere of Ar:O2=9:1, with the first stage being kept at 410°C for 1 hour and the second stage being kept at 600°C for 1 hour.

[0055] Step 3: Molding: inject the nanopowder into a rubber mold, apply a pressure of 150 MPa in a cold isostatic press and hold the pressure for 8 minutes to obtain a cylindrical body;

[0056] Step 4: Sintering treatment: Place the green body into a graphite mold and place it in an SPS furnace. Heat it to 1100°C at a rate of 150°C / min and hot press it for 1 hour under an axial pressure of 30 MPa. Then heat it to 1200°C for two-stage sintering and keep it warm for 1.5 hours under a vacuum of 5 Pa to obtain a cylindrical target.

[0057] Step 5: Precision machining: The sintered cylindrical target is cut with diamond wire and the surface is ground and polished to a roughness Ra ≤ 0.1 μm and a flatness error ≤ ± 0.05 mm to obtain the AZO target.

[0058] The performance test showed that the resistivity was 1.1×10 -4 Ω·cm, the average visible light transmittance is 87.2%, and the carrier concentration is 2.1×10 21 cm -3 , carrier mobility 14.8cm 2 / V·s, and its relative density is 97.8%.

[0059] Comparative Example 2

[0060] The traditional solid phase sintering method was used. The raw materials were micron-sized materials. ZnO with a particle size of 1 μm and Al2O3 with a particle size of 0.5 μm were used. The ratio was ZnO:Al2O3=97:3. The sintering temperature was 1300℃, the sintering time was 12 h, and the pressure was controlled at 50 MPa. The performance test of the prepared AZO target showed a resistivity of 2.3×10 -4 Ω·cm, the average visible light transmittance is 82.1%, and the relative density is 94.5%.

[0061] The performance tests of the AZO targets prepared in the above embodiments and comparative examples show that the targets prepared in Examples 1-2 and Comparative Example 1 have significantly better performance than the targets prepared by the traditional solid-phase sintering method; the targets prepared in Examples 1 and 2 with the addition of sintering aids have better performance than the targets prepared in Comparative Example 1 without the addition of sintering aids.

[0062] At the same time, by comparing the performance of the targets prepared with different material ratios in Example 1 and Example 2, it can be seen that the target prepared by mixing and sintering the base material, dopant and sintering aid in a ratio of 97.5%:2.2%:0.3% by mass has the best performance, which is the optimal parameter ratio.

[0063] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An AZO target with good photoelectric properties, characterized by: The invention comprises a matrix material, a dopant and a sintering aid in a mass percentage of 96%-98%:1.5%-3%:0.1%-0.5%, wherein the matrix material is high-purity ZnO, the dopant is Al2O3, and the sintering aid is a Bi2O3-Y2O3 composite aid, wherein the molar ratio of Bi2O3 to Y2O3 is 2-4:

1.

2. The AZO target material with good photoelectric performance according to claim 1, characterized in that: The resistivity of the target material is ≤9.6×10 -5 Ω·cm, average visible light transmittance ≥88%, carrier concentration 10 20 -10 21 cm -3 , carrier mobility ≥15cm 2 / V·s.

3. A process for preparing an AZO target material with good photoelectric properties, characterized in that: The following steps are involved: Step 1: Pre-treating the raw materials: weighing the zinc source powder, aluminum source powder and sintering aid according to the mass percentage, adding anhydrous ethanol as a dispersion medium and wet grinding to obtain a uniformly dispersed mixed slurry; Step 2: Primary calcination treatment: the mixed slurry is dried by rotary evaporation at 80-100°C, ground and passed through a 200-mesh sieve to obtain a nano-scale mixed powder with good fluidity, and the mixed powder is placed in a microwave oven for two-stage calcination to obtain a nano-powder; Step 3: Molding: inject the nanopowder into a rubber mold, apply a pressure of 100-200 MPa in a cold isostatic press and hold the pressure for 5-10 minutes to obtain a cylindrical body; Step 4: Sintering treatment: Place the green body into a graphite mold and place it in an SPS furnace. Heat it to 1100-1200°C at a rate of 100-200°C / min and hot press it under an axial pressure of 20-50 MPa for 1-2 hours. Then heat it to 1200-1400°C and sinter it in two stages and keep it at this temperature for 2-3 hours to obtain a cylindrical target. Step 5: Precision machining: The sintered cylindrical target is cut with diamond wire and the surface is ground and polished to a roughness Ra ≤ 0.1 μm and a flatness error ≤ ± 0.05 mm to obtain the AZO target.

4. The process for preparing an AZO target material with good photoelectric performance according to claim 3, characterized in that: In the step 1, the zinc source powder is ZnO powder with a particle size of ≤50nm and a purity of ≥99.99%, the aluminum source powder is Al2O3 powder with a particle size of ≤30nm, and the sintering aid is a composite powder of Bi2O3 and Y2O3 with a particle size of ≤50nm.

5. The process for preparing an AZO target material with good photoelectric performance according to claim 3, characterized in that: The wet grinding in step 1 uses zirconia balls, a ball-to-material ratio of 10:1, a rotation speed of 80-120 rpm, and a ball milling time of 6-12 h.

6. The process for preparing an AZO target material with good photoelectric performance according to claim 3, characterized in that: The volume ratio of the dispersion medium anhydrous ethanol to the mixture of the zinc source powder, the aluminum source powder and the sintering aid is 1:

3.

7. The process for preparing an AZO target material with good photoelectric performance according to claim 3, characterized in that: The microwave calcination in the second step is carried out in an atmosphere of Ar:O2=9:1, with the first stage being kept at 390-410°C for 1 hour, and the second stage being kept at 590-610°C for 2 hours.

8. The process for preparing an AZO target material with good photoelectric performance according to claim 3, characterized in that: After the second stage sintering in step 4, the temperature is kept under vacuum degree ≤ 5 Pa.

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