Cuprous iodide-based target material, method for preparing the same, and use thereof

Abstract

This invention provides a cuprous iodide-based target material, its preparation method, and its application, belonging to the field of target material technology. This invention employs chalcogenides, metal oxides, and alkali metal halides to dope cuprous iodide, and combines optimized powder processing and target sintering parameters to obtain a highly conductive cuprous iodide-based target material. The density of the cuprous iodide-based target material is 5.0~5.6 g / cm³. 3 With a grain size of 0.1–20 μm, the target material exhibits high density and high strength. The p-type transparent conductive film prepared from it has a mobility greater than 20 cm⁻¹. 2 / V·s, resistivity less than 10 ‑3 Ω cm, visible light transmittance greater than 80%, simultaneously meeting the requirements of high conductivity and high visible light transmittance.

Description

Technical Field

[0001] This invention belongs to the field of target technology, specifically relating to a cuprous iodide-based target, its preparation method, and its application. Background Technology

[0002] Traditional transparent conductive oxide thin films are mainly composed of indium oxide (In₂O₃)-based, zinc oxide (ZnO)-based, and tin oxide (SnO₂)-based materials. Among them, In₂O₃-based ITO thin films have become the most widely used transparent conductive oxide thin film material due to their advantages such as low resistivity, high bandgap, high transmittance, good abrasion resistance, and good chemical stability. Currently, the widely used transparent conductive thin films are all n-type materials, while the corresponding p-type materials have poor electrical properties or low visible light transmittance, which cannot reach the level of industrial application. Cuprous iodide (CuI)-based targets (CuI targets for short) to prepare transparent conductive films of cuprous iodide (CuI films for short) is a highly promising p-type transparent conductive thin film material. Its direct bandgap is 3.1 eV, and it has high transmittance in the visible and near-infrared regions; its carrier mass is only 0.3m₀, and it has high hole mobility (> 40 cm⁻¹). 2 / V·s) and hole concentration (> 10 19 cm -3 Furthermore, it possesses advantages such as being non-toxic and environmentally friendly, having abundant storage capacity, and being capable of low-temperature preparation, making it promising for applications in flat panel displays, solar cells, organic light-emitting diodes, low-emissivity glass, special functional window coatings, transparent thin-film transistors, and flexible electronic devices.

[0003] Cuprous iodide exhibits three crystal structures under normal pressure: below 643 K, it has a zincblende structure (γ-CuI); between 643 and 673 K, it has a wurtzite structure (β-CuI); and above 673 K, it has a rock salt structure (α-CuI). Its melting point is 605℃, and it evaporates in a vacuum environment above 300℃. As an indispensable raw material in magnetron sputtering technology, the quality of the sputtering target directly determines the performance of the prepared thin film and device. To prepare CuI targets suitable for industrial vacuum sputtering coating, it is urgent to develop a cuprous iodide target that produces transparent conductive films with low resistivity and high transmittance. Summary of the Invention

[0004] The purpose of this invention is to propose a cuprous iodide-based target material, its preparation method, and its application. By doping with specific amounts of chalcogenides, metal oxides, alkali metal halides, etc., and combining optimized powder processing and target sintering parameters, a highly conductive cuprous iodide-based target material is prepared to meet the requirements of industrial vacuum sputtering coating for target materials.

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

[0006] A method for preparing a cuprous iodide-based target material, characterized in that the method includes the following steps:

[0007] Step 1: Mixing the powder

[0008] The cuprous iodide powder and the additives are stirred and mixed evenly to obtain the first powder; the additives are copper sulfide, copper selenide, copper telluride chalcogenides, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, molybdenum oxide, gallium oxide, tin oxide, cuprous oxide, copper oxide, alkali metal halides or alkaline earth halides; the mass percentage of the additives is 0.1% to 20% of the cuprous iodide powder;

[0009] Step 2: Ball milling

[0010] The first powder is then poured into a ball mill, ethanol and a binder are added, along with milling balls. The powder solid content is controlled at 30-80%, and the mixture is milled for 3-48 hours to obtain the first slurry. The binder is water, anhydrous ethanol, polyethylene glycol, polyvinyl alcohol, or polyvinyl butyral. The amount of binder used is 0.1% to 10% of the powder mass.

[0011] Step 3: Drying the slurry

[0012] The first slurry was dried at a temperature of -40 to 200°C for 3 to 48 hours. After drying, the powder was sieved to obtain powder with a particle size of 0.5 to 8 μm; this powder was designated as the second powder.

[0013] Step 4: Shaping the raw blank

[0014] The second powder is loaded into a mold, and mechanical vibration or ultrasonic assistance is used to increase the tap density of the second powder in the mold. The mold is then pressurized to form a green body; the pressure used is 30~300MPa.

[0015] Step 5: Sintering

[0016] The green blank is placed in a uniform heating environment for sintering, and the cuprous iodide-based target material is obtained by vacuuming or introducing a circulating inert protective gas; wherein the sintering temperature is 200~600℃ and the holding time is 1~36 hours.

[0017] Furthermore, the purity of cuprous iodide in the powder used for target fabrication is at least 60%, by mass percentage.

[0018] Furthermore, the ball mill uses balls made of at least one of zirconium oxide, stainless steel, agate, and nylon, and the diameter of the balls is 2 to 10 mm.

[0019] Furthermore, the slurry drying method is at least one of spray drying, freeze drying, heat drying, and vacuum drying.

[0020] Furthermore, in the green blank forming process, the powder-filling mold includes a planar target forming mold and a tubular rubber mold, which can respectively form planar and hollow tubular green blanks.

[0021] Furthermore, in the green blank forming process, the pressure forming methods include cold isostatic pressing, warm isostatic pressing, and hot isostatic pressing.

[0022] Furthermore, the sintering process includes sintering in an inert atmosphere and vacuum sintering.

[0023] Furthermore, the inert protective gas is at least one of nitrogen and argon, and the gas flow rate is 1~100 sccm.

[0024] A cuprous iodide-based target material prepared by the above method.

[0025] An application of the cuprous iodide-based target in the preparation of p-type transparent conductive films.

[0026] Furthermore, the cuprous iodide target is cut and polished according to relevant requirements, and then assembled and bonded to obtain a sputtering target suitable for industrial production. Using the sputtering target, a p-type transparent conductive film is obtained by physical vapor deposition (PVD) sputtering, with a mobility of 1~20 cm⁻¹. 2 / V·s, resistivity 10 -4 ~10 -2 Ω cm, with a visible light transmittance of at least 80%.

[0027] The advantages of this invention compared to the prior art are:

[0028] (1) This invention uses specific amounts of chalcogenides, metal oxides, alkali metal halides, and alkaline earth metal halides to dope cuprous iodide, and combines this with optimized powder processing and target sintering parameters to prepare highly conductive cuprous iodide-based targets. The density of the cuprous iodide-based targets is 5.0~8 g / cm³. 3 The target material has the characteristic of high strength.

[0029] (2) The present invention utilizes a doped cuprous iodide target to deposit a p-type transparent conductive film by physical vapor deposition (PVD) sputtering, with a mobility of 1~20 cm⁻¹. 2 / V·s, resistivity 10 -4 ~10 -2With a visible light transmittance greater than 80%, this target material meets the requirements of both high conductivity and high visible light transmittance, exhibiting excellent optoelectronic properties. It can be directly applied in optoelectronic industries such as photovoltaic cells and displays. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a magnetron sputtering target with a diameter of 2 inches prepared in Example 1 of the present invention;

[0031] Figure 2 This is a schematic diagram of a magnetron sputtering target with a diameter of 2 inches prepared in Example 2 of the present invention;

[0032] Figure 3 This is a schematic diagram of a magnetron sputtering rotating target with a diameter of 12 cm and a length of 22 cm prepared in Example 3 of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Example 1

[0035] Based on atomic percentage, 90 at.% cuprous iodide powder and 10 at.% alumina powder are mixed evenly to obtain the first powder.

[0036] The first powder was then poured into a ball mill, and anhydrous ethanol and zirconia balls with a diameter of 4 mm were added. The powder solid content was controlled at 40 wt.%, and the mixture was ball-milled for 3 hours to obtain the first slurry. The binder was deionized water, and its content was 0.1% (by weight) of the cuprous iodide content.

[0037] The first slurry was placed in a forced-air drying oven and dried at 110°C for 40 hours to obtain the first dry powder.

[0038] The first dry powder is placed into a vibrating sieve to obtain a particle size D. 90 = ~5 μm of second dry powder;

[0039] The second dry powder is loaded into the mold and filled using ultrasonic assistance to increase the compaction density of the second dry powder in the mold. It is then placed in a cold isostatic press for molding. The molding pressure is 10 MPa and held for 10 minutes, then adjusted to 30 MPa and held for 15 minutes, and then the pressure is gradually reduced in increments of 5 MPa. After static pressing, a green blank is obtained as the target material blank.

[0040] The green blanks were placed in a sintering furnace for high-temperature sintering at 425°C for 6 hours. The sintering atmosphere was argon, with a gas flow rate of 4 sccm. The resulting bulk density was 5.2 g / cm³. 3 Cuprous iodide base Target material.

[0041] Then, the sputtering target is machined and bonded according to the corresponding drawings to obtain the sputtering target; its shape is shown in the figure. Figure 1 As shown.

[0042] In the coating process, a cuprous iodide sputtering target is mounted on a magnetron sputtering coating machine, and a transparent conductive thin film is obtained by sputtering using a DC magnetron sputtering coating machine. The film thickness is controlled at 100 nm, resulting in a mobility of ~15 cm⁻¹. 2 / V·s, resistivity ~3×10 -4 A p-type transparent conductive film with a visible light transmittance of greater than 83% (Ω cm).

[0043] Example 2

[0044] Based on atomic percentage, 80 at.% cuprous iodide powder, 10 at.% copper oxide powder, and 10 at.% copper sulfide powder are mixed evenly to obtain the first powder.

[0045] The first powder was then poured into a ball mill, anhydrous ethanol and zirconia balls with a diameter of 6 mm were added, and the powder solid content was controlled at 60% (by weight). The mill was then ball-milled for 20 hours to obtain the first slurry. The binder was polyvinyl alcohol, with a content of 5% (by weight) of cuprous iodide.

[0046] The first slurry was placed in a forced-air drying oven and dried at 180°C for 24 hours to obtain the first dry powder.

[0047] The first dry powder is placed into a vibrating sieve to obtain a particle size D. 90 = ~2 μm second dry powder;

[0048] The second dry powder is loaded into the mold and filled using ultrasonic assistance to increase the compaction density of the second dry powder in the mold. It is then placed in a cold isostatic press for molding. The molding pressure is 30 MPa and held for 10 minutes, then adjusted to 150 MPa and held for 5 minutes, and then the pressure is gradually reduced in increments of 10 MPa. After static pressing, a green blank is obtained as the target material blank.

[0049] The green blanks were placed in a sintering furnace for high-temperature sintering at 460°C for 20 hours. The sintering atmosphere was nitrogen, with a gas flow rate of 10 sccm. The resulting bulk density was 5.1 g / cm³. 3 Cuprous iodide-based target material.

[0050] Then, the sputtering target is machined and bonded according to the corresponding drawings to obtain the sputtering target; its shape is shown in the figure. Figure 2 As shown.

[0051] In the coating process, a cuprous iodide sputtering target is mounted on a magnetron sputtering coating machine, and a transparent conductive thin film is obtained by sputtering using a DC magnetron sputtering coating machine. The film thickness is controlled at 100 nm, resulting in a mobility of ~20 cm⁻¹. 2 / V·s, resistivity ~5×10 -4 A p-type transparent conductive film with a visible light transmittance of greater than 80% (Ω cm).

[0052] Example 3

[0053] Based on atomic percentage, 99 at.% cuprous iodide powder and 1 at.% copper bromide powder were mixed evenly to obtain the first powder.

[0054] The first powder was then poured into a ball mill, along with deionized water and 6 mm diameter zirconium oxide and nylon balls. The powder solid content was controlled at 80% (by weight), and the mixture was ball-milled for 30 hours to obtain the first slurry. The binder was anhydrous ethanol, with a content of 10% (by weight) of cuprous iodide.

[0055] The first slurry was placed in a freeze-drying oven and dried under vacuum and -40°C conditions for 24 hours to obtain the first dry powder.

[0056] The first dry powder is placed into a vibrating sieve to obtain a particle size D. 90 = ~4 μm second dry powder;

[0057] The second dry powder is loaded into the mold and filled using ultrasonic assistance to increase the compaction density of the second dry powder in the mold. It is then placed in a cold isostatic press for molding. The molding pressure is 50 MPa and held for 10 minutes, then adjusted to 300 MPa and held for 5 minutes, and then the pressure is gradually reduced in increments of 10 MPa. After static pressing, a green blank is obtained as the target material blank.

[0058] The green blanks were placed in a sintering furnace for high-temperature sintering at 350°C for 30 hours. The sintering atmosphere was nitrogen, with a gas flow rate of 50 sccm. A bulk density of 5.5 g / cm³ was obtained. 3 Cuprous iodide-based target material.

[0059] Then, the sputtering target is machined and bonded according to the corresponding drawings to obtain the sputtering target; its shape is shown in the figure. Figure 3 As shown.

[0060] In the coating process, a cuprous iodide sputtering target is mounted on a magnetron sputtering coating machine, and a transparent conductive thin film is obtained by sputtering using a DC magnetron sputtering coating machine. The film thickness is controlled at 100 nm, resulting in a mobility of ~11 cm⁻¹. 2 / V·s, resistivity ~1×10 -3 A p-type transparent conductive film with a visible light transmittance of greater than 85% (Ω cm).

[0061] The comparison of powder processing, powder drying, preform pressing and target sintering processes, and physical properties of cuprous iodide thin films obtained by target sputtering in the three embodiments of the present invention are respectively referred to in Tables 1, 2 and 3.

[0062] Table 1. Comparison of Powder Processes in Three Specific Examples

[0063] Table 2. Comparison of powder drying, preform pressing, and target sintering processes in three specific embodiments.

[0064] Table 3. Comparison of physical properties of cuprous iodide thin films obtained by sputtering target materials using three specific embodiments.

[0065] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method of producing a cuprous iodide-based target material, characterized by: Includes the following steps, Step 1: Mixing the powder The cuprous iodide powder and the additives are stirred and mixed evenly to obtain the first powder; the additives are copper sulfide, copper selenide, copper telluride chalcogenides, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, molybdenum oxide, gallium oxide, tin oxide, cuprous oxide, copper oxide, alkali metal halides or alkaline earth halides; the mass percentage of the additives is 0.1% to 20% of the cuprous iodide powder; Step 2: Ball milling The first powder is then poured into a ball mill, ethanol and binder are added, and milling balls are added. The powder solid content is controlled at 30-80%, and the mixture is milled for 3-48 hours to obtain the first slurry. The binder is water, anhydrous ethanol, polyethylene glycol, polyvinyl alcohol, or polyvinyl butyral. The amount of binder used is 0.1% to 10% of the powder mass; Step 3: Drying the slurry The first slurry was dried at a temperature of -40 to 200°C for 3 to 48 hours. After drying, the powder was sieved to obtain powder with a particle size of 0.5 to 8 μm; this powder was designated as the second powder. Step 4: Shaping the raw blank The second powder is loaded into a mold, and mechanical vibration or ultrasonic assistance is used to increase the tap density of the second powder in the mold. The mold is then pressurized to form a green body; the pressure used is 30~300MPa. Step 5: Sintering The green blank is placed in a uniform heating environment for sintering, and the cuprous iodide-based target material is obtained by vacuuming or introducing a circulating inert protective gas; wherein the sintering temperature is 250~500℃ and the holding time is 1~36 hours.

2. The method for preparing the cuprous iodide-based target according to claim 1, characterized in that, The purity of the cuprous iodide used must be at least 60%, by mass percentage.

3. The method for preparing the cuprous iodide-based target according to claim 1, characterized in that, The ball mill uses balls made of at least one of zirconium oxide, stainless steel, agate, and nylon, with a diameter of 2 to 10 mm.

4. The method for preparing the cuprous iodide-based target according to claim 1, characterized in that, The slurry drying method is at least one of spray drying, freeze drying, heat drying, and vacuum drying.

5. The method for preparing the cuprous iodide-based target according to claim 1, characterized in that, In the green blank forming process, the powder-filled mold includes a planar target forming mold and a tubular rubber mold, which can respectively form planar and hollow tubular green blanks.

6. The method for preparing the cuprous iodide-based target material according to claim 1, characterized in that, In the green body forming process, the pressure forming methods include cold isostatic pressing, warm isostatic pressing, and hot isostatic pressing.

7. The method for preparing the cuprous iodide-based target material according to claim 1, characterized in that, The inert protective gas is at least one of nitrogen and argon, and the gas flow rate is 1~100 sccm.

8. A cuprous iodide-based target material prepared by the method of claim 1.

9. The application of the cuprous iodide-based target material of claim 8 in the preparation of p-type transparent conductive films.

10. The application according to claim 9, characterized in that, The cuprous iodide target is cut and polished according to relevant requirements, and then assembled and bonded to obtain a sputtering target suitable for industrial production. Using the sputtering target, a p-type transparent conductive film is obtained by physical vapor deposition, with a mobility of ~20 cm⁻¹. 2 / V·s, resistivity 10 -4 ~10 -2 Ω cm, visible light transmittance greater than 80%.

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