A LaSm co-doped ITO target material and its preparation method and application

Abstract

The invention discloses a LaSm co-doped ITO target material and a preparation method and application thereof, belonging to the technical field of ITO target materials. Nano-ITO powder, nano-LaSm(BO3)2 powder and acetic acid solution are ball-milled and mixed into a slurry. The mixture is kept in a mold at 480±5MPa and 400-420°C for 60-80min, cooled naturally, and a green body is obtained. The green body is sintered at 1350-1400°C for 3-3.5h in an oxygen atmosphere to prepare the LaSm co-doped ITO target material. The sintering temperature is lower than the commonly used 1550°C to avoid excessive grain size and density, thereby preventing an impact on the transmittance of a thin film after sputtering. The addition of nano-LaSm(BO3)2 powder helps to increase or decrease the transmittance of the sputtered film. The sputtered ITO film of the LaSm co-doped ITO target material can be used as an anti-reflection film for a solar cell silicon wafer, thereby reducing the internal resistance of the cell and improving the output power of the solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of ITO target materials, and in particular relates to a LaSm co-doped ITO target material and a preparation method and application thereof. Background Art

[0002] ITO (indium tin oxide) targets are used in thin-film deposition techniques such as physical evaporation and magnetron sputtering, and play a vital role in the electronics industry. Composed of indium and tin oxides in appropriate proportions, ITO targets exhibit transparent conductivity and are therefore suitable for the production of transparent electrodes in applications such as liquid crystal displays, organic light-emitting diodes, touch screens, and solar cells.

[0003] During the production of solar panels, silicon wafers typically undergo cleaning, texturing, diffusion, and anti-reflection coating deposition. Anti-reflection coating is a thin-film coating used to reduce reflections on the surface of optical devices, thereby improving the transmittance and performance of optical components. Commonly used anti-reflection coatings are made of silicon nitride. Although ITO film also has good light transmittance, its reflectivity is lower than that of silicon nitride film, and its anti-reflection effect is not as good, which can affect the efficiency of solar cells. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a LaSm co-doped ITO target material to solve the transmittance problem of conventional ITO film; the second purpose is to provide a preparation method of LaSm co-doped ITO target material; the third purpose is to provide an application of LaSm co-doped ITO target material.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A LaSm co-doped ITO target material, the raw materials of which include nano ITO powder and nano LaSm (BO3)2 powder.

[0007] A method for preparing a LaSm co-doped ITO target comprises the following steps:

[0008] Step 1: Add lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, glycine and boric acid to a reactor, then add deionized water, stir at 200-500 r / min for 30-60 min to obtain a mixed solution, put the mixed solution into a crucible and transfer it to a muffle furnace, heat it to 800-850°C at a rate of 3-5°C / min and keep it warm for 3-4 hours, and after natural cooling, ball mill the product and sieve it to obtain nano-LaSm(BO3)2 powder with a particle diameter of 30-40 nm;

[0009] Step 2: Add tin tetrachloride pentahydrate, indium nitrate and deionized water to a reactor and stir and mix, then add 25% ammonia water and adjust the pH value to 10, stir at 200-500 r / min for 120-150 min, then let it stand for 6-10 h, then centrifuge the reaction solution, collect the precipitate and wash it with deionized water 3-5 times, dry it, put the precipitate into a crucible and transfer it to a muffle furnace, in an oxygen atmosphere, heat it to 500°C at 3-5°C / min and keep it warm for 2-2.5 h, cool it naturally, then ball-mill the product and sieve it to obtain a nano-ITO powder with a particle diameter of 20-30 nm;

[0010] Step 3: Add nano-ITO powder, nano-LaSm(BO3)2 powder and 60% acetic acid solution into a ball mill and mix them, adjust the solid content to 65-70wt% to obtain a slurry, transfer the slurry into a mold, and heat it to 400-420℃ at a rate of 10℃ / min under a pressure of 480±5MPa and keep it at this temperature for 60-80min, and cool it naturally to obtain a green body;

[0011] Step 4: Transfer the green body to a sintering furnace and, in an oxygen atmosphere, heat it to 1350-1400°C at a rate of 2-5°C / min and hold it there for 3-3.5 hours. Then, cool it to 350-400°C at a rate of 10°C / min and allow it to cool naturally to obtain a LaSm co-doped ITO target. This LaSm co-doped ITO target can be used for sputtering anti-reflection coatings on solar cell silicon wafers.

[0012] Furthermore, the usage ratio of lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, glycine, boric acid and deionized water is 34.3 g: 44.45 g: 25 g: 12.37 g: 250-300 mL.

[0013] Furthermore, the usage ratio of tin tetrachloride pentahydrate, indium nitrate and deionized water is 18.32 g:195.44 g:1000 mL.

[0014] Furthermore, the usage ratio of nano-ITO powder and nano-LaSm(BO3)2 powder is 113.74g:13.76-18.18g.

[0015] Beneficial effects of the present invention:

[0016] The LaSm co-doped ITO target material of the present invention is made from nano-ITO powder and nano-LaSm(BO3)2 powder. The addition of nano-LaSm(BO3)2 powder helps increase or decrease the transmittance of the sputtered film. After heat and pressure treatment at 500°C in a mold, a green body with good bonding strength is produced. This eliminates the need for an organic binder, reduces the formation of pores, and helps ensure the density of the LaSm co-doped ITO target material after sintering. Furthermore, the sintering process uses a temperature lower than the commonly used 1550°C, which helps prevent excessive grain size and density, preventing the transmittance of the sputtered film from being affected.

[0017] During the preparation of nano-LaSm(BO3)2 powder, glycine is used as a combustion agent. During the heat-insulating combustion process, gases such as water, carbon dioxide and nitrogen oxides are produced to form a porous rare earth borate sinter, which is convenient for ball milling. The borate contains boric acid groups formed by sp2 hybridization of boron and oxygen, which has high reducing properties and can prevent the rare earth metal ions in the nano-LaSm(BO3)2 powder from being oxidized during the sintering process, thereby helping to improve its stability.

[0018] The sputtered ITO film of LaSm co-doped ITO target is used as an anti-reflection film for solar cell silicon wafers, which can reduce the internal resistance of the cell and thus increase the output power of the solar cell. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] Example 1

[0021] This embodiment provides a LaSm co-doped ITO target, including the following implementation steps:

[0022] Step 1: Add 68.6 kg of lanthanum nitrate hexahydrate, 88.9 kg of samarium nitrate hexahydrate, 50 kg of glycine and 24.74 kg of boric acid into a reactor, then add 500 L of deionized water, stir at 200 r / min for 30 minutes to obtain a mixed solution, put the mixed solution into a crucible and transfer it to a muffle furnace, heat it to 800 ° C at a rate of 3 ° C / min and keep it warm for 3 hours, and after natural cooling, ball mill the product and sieve it to obtain nano LaSm (BO3) 2 powder with a particle diameter of 30 nm.

[0023] Step 2: Add 18.32 kg of tin tetrachloride pentahydrate, 195.44 kg of indium nitrate and 1000 L of deionized water into the reactor and stir to mix, then add 25% ammonia water and adjust the pH value to 10, stir at 200 r / min for 120 min, then let it stand for 6 h, then centrifuge the reaction solution, collect the precipitate and wash it with deionized water 3 times, dry it, put the precipitate into a crucible and transfer it to a muffle furnace, in an oxygen atmosphere, heat it to 500 ° C at 3 ° C / min and keep it warm for 2 h, and after natural cooling, ball mill the product and sieve it to obtain nano ITO powder with a particle diameter of 20-30 nm.

[0024] Step 3: Add 11.374 kg of nano-ITO powder, 1.376 kg of nano-LaSm(BO3)2 powder and 60% acetic acid solution with the same mass as the two powders into a ball mill and mix them, adjust the solid content to 65 wt% to obtain a slurry, transfer the slurry to a mold, and heat it to 400 ° C at a rate of 10 ° C / min under a pressure of 480 ± 5 MPa and keep it warm for 60 minutes, and cool it naturally to obtain a green body; transfer the green body to a sintering furnace, in an oxygen atmosphere, heat it to 1350 ° C at a rate of 2 ° C / min and keep it warm for 3 hours, then cool it to 350 ° C at a rate of 10 ° C / min, and cool it naturally to obtain a LaSm co-doped ITO target.

[0025] The average grain size of the LaSm co-doped ITO target was 6.2 μm as determined by scanning electron microscopy, and the relative density of the target was 7.9296 g / cm3 as determined by the Archimedean drainage method. 3 .

[0026] Example 2

[0027] This embodiment provides a LaSm co-doped ITO target, including the following implementation steps:

[0028] Step 1: Add 68.6 kg of lanthanum nitrate hexahydrate, 88.9 kg of samarium nitrate hexahydrate, 50 kg of glycine and 24.74 kg of boric acid into a reactor, then add 550 L of deionized water, stir at 350 r / min for 45 minutes to obtain a mixed solution, put the mixed solution into a crucible and transfer it to a muffle furnace, heat it to 825 ° C at a rate of 4 ° C / min and keep it warm for 3.5 hours, and after natural cooling, ball mill the product and sieve it to obtain nano LaSm (BO3) 2 powder with a particle diameter of 30-40 nm.

[0029] Step 2: Add 18.32 kg of tin tetrachloride pentahydrate, 195.44 kg of indium nitrate and 1000 L of deionized water into the reactor and stir to mix, then add 25% ammonia water by mass and adjust the pH value to 10, stir at 350 r / min for 135 min, then let it stand for 8 h, then centrifuge the reaction solution, collect the precipitate and wash it with deionized water 4 times, dry it, put the precipitate into a crucible and transfer it to a muffle furnace, in an oxygen atmosphere, heat to 500 ° C at 4 ° C / min and keep it warm for 2.3 h, and after natural cooling, ball mill the product and sieve it to obtain a nano ITO powder with a particle diameter of 20-30 nm.

[0030] Step 3: Add 11.374 kg of nano-ITO powder, 1.597 kg of nano-LaSm(BO3)2 powder and 60% acetic acid solution with the same mass as the two powders into a ball mill and mix them, adjust the solid content to 68 wt% to obtain a slurry, transfer the slurry to a mold, and heat it to 410 ° C at a rate of 10 ° C / min under a pressure of 480 ± 5 MPa and keep it warm for 70 minutes, and cool it naturally to obtain a green body; transfer the green body to a sintering furnace, in an oxygen atmosphere, heat it to 1380 ° C at a rate of 4 ° C / min and keep it warm for 3.2 hours, then cool it to 380 ° C at a rate of 10 ° C / min, and cool it naturally to obtain a LaSm co-doped ITO target.

[0031] The average grain size of the LaSm co-doped ITO target was 6.4 μm as determined by scanning electron microscopy, and the relative density of the target was 7.9357 g / cm3 as determined by the Archimedean drainage method. 3 .

[0032] Example 3

[0033] This embodiment provides a LaSm co-doped ITO target, including the following implementation steps:

[0034] Step 1: Add 68.6 kg of lanthanum nitrate hexahydrate, 88.9 kg of samarium nitrate hexahydrate, 50 kg of glycine and 24.74 kg of boric acid into a reactor, then add 600 L of deionized water, stir at 500 r / min for 60 minutes to obtain a mixed solution, put the mixed solution into a crucible and transfer it to a muffle furnace, heat it to 850 ° C at a rate of 5 ° C / min and keep it warm for 4 hours, and after natural cooling, ball mill the product and sieve it to obtain nano LaSm (BO3) 2 powder with a particle diameter of 30-40 nm.

[0035] Step 2: Add 18.32 kg of tin tetrachloride pentahydrate, 195.44 kg of indium nitrate and 1000 L of deionized water into the reactor and stir to mix, then add 25% ammonia water and adjust the pH value to 10, stir at 500 r / min for 150 min, then let it stand for 10 h, then centrifuge the reaction solution, collect the precipitate and wash it with deionized water 5 times, dry it, put the precipitate into a crucible and transfer it to a muffle furnace, in an oxygen atmosphere, heat to 500 ° C at 5 ° C / min and keep it warm for 2.5 h, and after natural cooling, ball mill the product and sieve it to obtain a nano ITO powder with a particle diameter of 30 nm.

[0036] Step 3: Add 11.374 kg of nano-ITO powder, 1.818 kg of nano-LaSm(BO3)2 powder and 60% acetic acid solution with the same mass as the two powders into a ball mill and mix them, adjust the solid content to 70 wt% to obtain a slurry, transfer the slurry to a mold, and heat it to -420 ° C at a rate of 10 ° C / min under a pressure of 480 ± 5 MPa and keep it warm for 80 minutes, and cool it naturally to obtain a green body; transfer the green body to a sintering furnace, in an oxygen atmosphere, heat it to 1400 ° C at a rate of 5 ° C / min and keep it warm for 3.5 hours, then cool it to 400 ° C at a rate of 10 ° C / min, and cool it naturally to obtain a LaSm co-doped ITO target.

[0037] The average grain size of the LaSm co-doped ITO target was 6.5 μm as determined by scanning electron microscopy, and the relative density of the target was 7.9376 g / cm3 as determined by the Archimedean drainage method. 3 .

[0038] Comparative Example 1: Based on Example 5, the nano-LaSm(BO3)2 powder was replaced with a mixed powder of lanthanum oxide and samarium oxide with a La:Sm atomic ratio of 1:1, and the other steps remained unchanged to prepare a LaSm co-doped ITO target.

[0039] The average grain size of the LaSm co-doped ITO target was 5.4 μm as determined by scanning electron microscopy, and the relative density of the target was 9.2659 g / cm3 as determined by the Archimedean drainage method. 3 .

[0040] Comparative Example 2: Based on Example 5, the sintering temperature of the green body in step 3 was increased from 1400° C. to 1550° C., and the other steps remained unchanged to prepare a LaSm co-doped ITO target.

[0041] The average grain size of the LaSm co-doped ITO target was determined to be 7.3 μm by scanning electron microscopy, and the relative density of the target was determined to be 8.5483 g / cm by Archimedes drainage method. 3 .

[0042] Comparative Example 3: Based on Example 5, no nano-LaSm(BO3)2 powder was added, and the other steps remained unchanged to prepare an ITO target.

[0043] The average size of the ITO target grains was determined to be 6.4 μm by scanning electron microscopy, and the relative density of the target was determined to be 8.2325 g / cm by Archimedes drainage method. 3 .

[0044] The LaSm co-doped ITO targets of Examples 1-3 and Comparative Examples 1-2 were sputtered onto PC films using magnetron sputtering to a thickness of 50 nm. The PC films exhibited a visible light transmittance of 98% at a wavelength of 600 nm. The visible light transmittance of the PC films sputtered with the different LaSm co-doped ITO targets at a wavelength of 600 nm was measured. The results are shown in Table 1.

[0045] Table 1

[0046]

[0047] As can be seen from Table 1, the visible light transmittance of the sputtered PC films in Examples 1 to 3 at a wavelength of 600 nm is not affected, indicating that the LaSm co-doped ITO target after nano-LaSm(BO3)2 powder can be used to prepare anti-reflection films for solar cell silicon wafers. In Comparative Example 1, doping with rare earth oxides will reduce the transmittance of the sputtered PC film. Comparative Example 2 shows that excessive density and grain size will also affect the transmittance of the sputtered PC film.

[0048] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0049] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a LaSm co-doped ITO target, characterized in that: The steps include: Step 1: Add lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, glycine, boric acid and deionized water into a reactor, stir at 200-500 r / min for 30-60 min, and then put the obtained mixed solution into a crucible and transfer it to a muffle furnace. Heat it to 800-850°C at a rate of 3-5°C / min and keep it at that temperature for 3-4 hours. Cool it naturally, ball mill it, and sieve it to obtain nano-LaSm(BO3)2 powder. Step 2: ball-milling nano-ITO powder, nano-LaSm (BO3) 2 powder and 60wt% acetic acid solution, adjusting the solid content to 65-70wt% to obtain a slurry, and then transferring it to a mold. Under a pressure of 480±5MPa, the temperature is increased to 400-420℃ at a rate of 10℃ / min and maintained at this temperature for 60-80min, and naturally cooled to obtain a green body. The amount ratio of the nano-ITO powder to the nano-LaSm (BO3) 2 powder is 113.74g:13.76-18.18g; the particle diameter of the nano-LaSm (BO3) 2 powder is 30-40nm. Step 3: Transfer the green body to a sintering furnace, and in an oxygen atmosphere, heat it to 1350-1400°C at a rate of 2-5°C / min and keep it warm for 3-3.5h, then cool it to 350-400°C at a rate of 10°C / min, and cool it naturally to obtain a LaSm co-doped ITO target.

2. The method for preparing a LaSm co-doped ITO target according to claim 1, wherein: The usage ratio of lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, glycine, boric acid and deionized water in step 1 is 34.3 g: 44.45 g: 25 g: 12.37 g: 250-300 mL.

3. The method for preparing a LaSm co-doped ITO target according to claim 1, wherein: The nano ITO powder is prepared by the following steps: Tin tetrachloride pentahydrate, indium nitrate and deionized water were stirred and mixed, and then the pH value was adjusted to 10 with 25wt% ammonia water. The mixture was stirred at 200-500r / min for 120-150min, allowed to stand for 6-10h, and centrifuged. The precipitate was collected, washed, and dried. The precipitate was placed in a crucible and transferred to a muffle furnace. In an oxygen atmosphere, the temperature was increased to 500℃ at 3-5℃ / min and kept at this temperature for 2-2.5h. The mixture was naturally cooled, ball-milled, and sieved to obtain nano-ITO powder.

4. The method for preparing a LaSm co-doped ITO target according to claim 3, wherein: The usage ratio of the tin tetrachloride pentahydrate, indium nitrate and deionized water is 18.32 g:195.44 g:1000 mL.

5. The method for preparing a LaSm co-doped ITO target according to claim 3, wherein: The particle diameter of the nano-ITO powder is 20-30 nm.

6. A LaSm co-doped ITO target, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the LaSm co-doped ITO target according to claim 6 in sputtering anti-reflection coating on solar cell silicon wafers.

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