TW201343557A - A low-cost method to prepare Ga-containing powders involving compounds, alloys, and intermetallic materials - Google Patents

Abstract

Thin-film Cu(In, Ga)Se2-based solar cells and the III-V laser diodes of GaN, InGaN, GaAs etc. for the light-emitting purpose all involve the Ga element. In this invention, a cost-effective and unique processing method has been developed for synthesizing the Ga-containing alloys, compounds, and Intermetallic compounds in the powder form. Due to its low melting temperature of 29 DEG C, Ga metal as an ingot can not be used for powder processing. Ga needs in the forms of chloride, sulfate, or metalorganic compounds for the chemical reactions. Ga needs to be dissolved in solvents in order for chemical synthesis. Ga compounds can be formed by casting to form ingots instead of powder. Ga needs in the forms of dangerous trimethyl gallium or trimethyl gallium in order to be used for metalorganic chemical vapor deposition of GaAs, GaN, AlGaInP thin films or powders. If the Ga-containing compounds can not synthesized by powder processing, the cost for its applications in solar cells and LEDs will be very high and its processing needs to be careful due to the toxicity of its precursors. In this invention, a shear scratch procedure is needed in order to extend the Ga metal and to blend with the second powders (X). After this mixing stage, a reaction at 200 to 1000 DEG C in protective atmosphere is conducted to form the GaX powders. If the reaction is conducted in air, Ga2O3 or Ga-X oxides can be obtained. To explain the feasibility of this invention, we demonstrate different kinds of Ga-containing powders involving, alloy and ceramic, oxide and non-oxide, nitride, sulfide, phosphide, selenides, intermetallic compound, Cu(In, Ga)Se2 etc. A general formula of GaX is used to present our synthesized powders, where X is symbolized for different kinds of materials in powder form.

Description

Preparation of gallium-containing compounds, alloys and mesometallic powders by a low-cost powder technology

Due to the energy crisis, everyone has invested in the research and development of solar cells and III-V semiconductors. At present or in the next few years, crystallization of solar cells is still the mainstream of the market, but the demand for solar energy will be higher, and the use of ruthenium will be driven. For example, the average crystal 矽 is about 200 μm, and the polycrystal is about 200 μm. With a thickness of 240 μm, excessive waste rate is generated in the process. Therefore, thinning of solar cells has become one of the research priorities. Among thin-film solar cells, copper indium gallium selenide (CIGSe) has advantages in this respect, and its conversion efficiency is currently up to 19.9% conversion efficiency, so copper indium gallium selenide (Cu ( In, Ga) Se ₂ , CIGSe) plays a very important role in the development of thin-film solar cells, and has the opportunity to become the mainstream of the next generation of solar energy.

Another popular III-V semiconductor industry is also in great need of related gallium compounds, from red-emitting gallium compounds (GaAs and AlGaAs), green-light gallium compounds (InGaN/GaN, GaP, AlGaInP and AlGaP), blue gallium Compounds (InGaN) and even the gallium-emitting compound (InGaN) require the use of related gallium compounds. At present, the raw materials for preparing III-V semiconductors are extremely expensive and expensive, and the synthesis of the compounds is also It involves raw materials that are not environmentally friendly.

Therefore, gallium-containing compounds or gallium-containing metals are important industrial raw materials. In the solar industry, if the gallium-containing compound or the gallium-containing alloy can be used as a powder raw material, the p-type absorption layer required for the thin film solar cell can be produced by physical vapor deposition of the metal target and the compound target by the powder technology. Alternatively, a p-type absorption layer may be formed by a printing method plus a sintering step using a powder raw material process ink. In the case of the III-V semiconductor industry, if a chemical vapor deposition process that uses high-risk and synthetic start-up substances involving environmentally harmful substances is converted to a physical vapor deposition method, target sputtering is performed using a gallium-containing powder raw material or Evaporation will minimize the safety of the production plant and the impact on the environment.

In view of the fact that governments around the world have invested a lot of manpower and capital to develop solar and semiconductor raw materials, and among the chemical materials, gallium is one of the most difficult materials to be processed. Gallium has a very low melting point (29 ° C) and extremely high surface tension, low temperature. Because the surface tension is extremely large, ingot-like agglomerates are formed, and it is difficult to react with other elements to form a compound, and the reactants are often generated only on the surface, but the internal gallium is strongly cohesive, and does not participate in the reaction and remains in a metallic state. Only gallium is formed into a powdery shape, and has a high surface area to fully react with other reactive materials to form a product of the correct metering ratio. Traditionally, it is not possible to produce a gallium-related powder raw material by a powder process. For example, when a gallium-containing alloy or a mesometallic compound is produced by a high-temperature smelting method, a high-pressure spray of an ingot or a high-temperature slurry is obtained, and the micron-scale is coarser. Powder. The desired gallium-containing compound is usually produced by (1) chemical synthesis, and the starting chemical materials such as GaCl ₃ , gallium alkoxides, gallium acetylacetonate, gallium nitrate, gallium sulfate are not cheap, and an organic solvent is used in the preparation process. Act as a buffer solvent or protect the role of powder (such as oleylamine, toluene, etc.) to ensure the preparation of better crystallinity and finer powder, but the residual solvent is not easy to clean, and there is waste treatment and Environmental pollution considerations, the large amount of waste liquid after the reaction of the precursor solution in the container contains many harmful substances, and if it is not handled properly, it will cause serious environmental pollution; (2) Preparation of gas phase reaction synthesis method The use of volatile precursors such as gallium dimethylamide, gallium diethylamide, which is costly, corrosive, flammable, or toxic, resulting in high cost of the formed gallium compound powder and high cost of selling, high purity powder can be obtained However, mass production is not easy.

Technical advantages of the present invention:

(1) Wide range of use: In the technique of the present invention, as long as the solid powder of the desired ratio is selected and mixed with the gallium ingot, the desired powder can be formed. In other words, most of the solid elements in the periodic table can be Selected to prepare gallium-containing powders. For example, the technology has successfully produced ultra-pure powders that are commercially available, such as the compound semiconductor gallium phosphide (GaP compound semiconductor), and the commercially available powder magnesium gallium intercalation metal. Compound (GaMg intermetallic compound), and gallium copper alloy (Ga-Cu alloy). For non-solid elements such as nitrogen (N), it is also possible to use a small amount of purchased GaN powder, mixed with a gallium ingot, and then reacted at 800 ° C or higher in an NH ₃ atmosphere to obtain an important GaN of a blue LED.

(2) Simple process and low raw material cost: the raw materials used in the preparation process are simple, only need to use cheaper gallium ingots and various elemental powders (for example: copper, phosphorus, selenium, arsenic, antimony, magnesium, aluminum, After sufficient mixing of a variety of different metals or different compounds, the homogeneous mixed powder is placed in a high-temperature atmosphere furnace and heated to a suitable temperature for 0.5-2 hours to prepare the desired compound and alloy. , a metal compound powder. The table below lists the unit price of chemical-grade reagents sold by pharmaceutical manufacturers. The commercially available gallium-containing powder materials are limited, and most of them are not sold.

(3) Environmentally friendly process: The present invention uses a process similar to powder metallurgy to react the mixed powder to form a gallium-containing product, which is a dry process, so the environmental protection problem of no chemical and waste liquid subsequent treatment can be greatly reduced. Use of chemicals.

(4) Residual impurities-free: Synthetic synthesis of powders containing gallium-containing powders can obtain nanometer-sized compound powders, but it is often necessary to use oleylamines as solvents and coupling agents in the heating conditions for the process, due to the nanometer The graded synthetic powder has strong adsorption force on the long-chain amine-based solution, which causes the organic matter to easily remain in the powder of the compound semiconductor material, thereby causing material contamination problems in subsequent processes.

[1] Process steps: 1. Powder mixing pre-preparation for scraper shear:

(1) Gallium element is an element with extremely low melting point and high surface tension. It exists in the form of ingot at room temperature, so it cannot exist in powder form, and it cannot react with other elements in powder metallurgy. . In the process of the present invention, first, the gallium element is still in a solid state, and the required gram weight is measured on the scale of the balance, and then the solid gallium ingot is placed on a substrate (for example, a glass piece) having a temperature of more than 30 ° C, so that the gallium element is solid. After the gallium element is completely converted into a liquid state, the blade is applied to the liquid gallium by using a scraper tool on the substrate to apply the blade shear force to the liquid gallium to facilitate the deployment of the liquid gallium, as shown in FIG.

(2) As the scraper is applied to the liquid gallium back and forth, the liquid gallium is gradually spread on the substrate, and the action is continued until the liquid gallium is completely unfolded and attached to the substrate, and no gallium beads are present. As shown in Figure 2, at this time, the substrate still needs to maintain a temperature greater than 30 °C.

(3) When it is confirmed that the liquid gallium has completely spread on the substrate, the elemental powder to be reacted (for example: copper, phosphorus, selenium, arsenic, antimony, magnesium, aluminum, carbon powder, etc.) is weighed according to the metering ratio. After the weight, sprinkle it over the unfolded gallium piece, as shown in Figure 3 below.

(4) After the element powder to be reacted is sprinkled over the unfolded liquid gallium piece, a shear stress is applied between the liquid gallium and the elemental powder to be reacted by the action of the scraper left and right. In order to prevent the unfolding of the liquid gallium from being destroyed, on the other hand, the elemental powder of the reaction is repeatedly tumbling on the unrolled liquid gallium, so that the liquid gallium is adhered to the elemental powder to be reacted, and the process is continued. Action (applying shear stress to the left and right) to ensure that the surface of the elemental powder to be reacted is evenly adhered to liquid gallium. The process schematic is shown in Figure 4.

(5) Continuously continue the above process until it is found that the surface of the element to be reacted is full of liquid gallium, and at the same time, the amount of liquid gallium is also found to be significantly reduced on the substrate. The blade is continuously applied with shearing stress to roll the elemental powder to be reacted and the powder to be reacted with liquid gallium on the surface. The main purpose is to ensure that all the powder surfaces of the element to be reacted are uniformly adsorbed. The liquid gallium is then placed in a high-temperature furnace in the atmosphere to form a gallium-containing compound or alloy, as shown in FIG.

(6) After the blade is applied back and forth between the elemental powder and the liquid gallium to be reacted, the surface of the element to be reacted is uniformly filled with liquid gallium, and then the mixing process is stopped, and simultaneously stopped. The substrate is heated, and after the substrate temperature is cooled to room temperature, the powder wrapped by the liquid gallium is taken out, and the powder to be reacted by the liquid gallium is scraped off by the scraping tool to ensure that the weight of the gallium element is not reduced. There are too many losses in the pre-operation, resulting in errors, as shown in Figure 6.

(7) The mixed powder which is thoroughly mixed by the pre-process operation (the reaction powder is wrapped by gallium) is placed in a clean glass jar, as shown in Fig. 7, and at the same time, it is checked whether there is still unevenness in the mixed powder. Powder, for example: pure liquid gallium particles and elemental powder to be reacted. If this phenomenon occurs, the mixed powder is immediately poured back onto the substrate, and heated to above 30 ° C, and the above-mentioned shearing powder is applied. The process of the body is used to mix the powder until it is determined that the uneven powder cannot be observed, and then the mixed powder device glass jar is awaiting the next stage of reaction.

2. The reaction step of mixing the powder: the powder (the elemental powder of the gallium-wrapped desired reaction) uniformly mixed in the previous stage (the powder mixing operation of the blade shearing force) is placed in a crucible and sent to a high temperature atmosphere. The tube furnace reacts as shown in Figure 8. The reaction steps are as follows:

(1) First, the vacuum of the tubular furnace has been reduced to reduce the amount of pollution in the air in the cavity.

(2) Passing the evacuated tube furnace into an argon (Ar), argon (Ar-H ₂ ) mixed gas as a shielding gas to an overpressure (greater than one atmospheric pressure) to ensure that external oxygen cannot enter the tube. Type furnace cavity to avoid oxidation.

(3) When the supply of protective gas and the overpressure (greater than one atmospheric pressure) are determined to be stable, the temperature can be raised to a predetermined temperature, and the temperature can be maintained for 0.5 to 3 hours. This new technology is different from high-temperature smelting, which needs to be heated to nearly a thousand degrees. Most of the reaction temperature of this technology only needs to be lower than the reaction temperature of 700 ° C, depending on the elemental powder to be reacted.

[2] Example: Example 1 Ga ₂ Se ₃ compound powder preparation:

(1) The Ga ₂ Se ₃ powder calculates the grammage required for Ga and Se according to 2:3 molar ratio.

(2) Mixing the gallium ingot and the selenium powder by the pre-processing method described in the first section.

(3) The powder of the liquid gallium-coated selenium powder uniformly mixed is prepared under the protective gas by a two-stage simmering method at 350 ° C for one hour and thirty minutes with 500 ° C for one hour and thirty minutes. Ga ₂ Se ₃ powder. As shown in Figures IX to XI, the X-ray structure diffraction analysis confirmed that there was no miscellaneous, and was supplemented by the analysis of scanning electron microscope images and optical images.

Example 2 Preparation of Cu(In,Ga)Se ₂ (CIGSe) compound powder:

(1) First, three compounds were prepared, which were Cu ₂ Se, In ₂ Se ₃ and Ga ₂ Se _{3 , respectively} .

(2) The Cu ₂ Se Imol ratio is used to calculate the gram weight required for Cu and Se, and then uniformly mixed and then held in a high temperature tubular furnace at 200 ° C for 3 hours to prepare Cu ₂ Se powder.

(3) In ₂ Se ₃ is calculated by the molar ratio of In and Se, and then uniformly mixed and then subjected to two-stage calcination in a high-temperature tubular furnace at 250 ° C for 1 hour and 450 ° C for 1 hour. Then, the In ₂ Se ₃ powder can be prepared.

(4) Ga ₂ Se _{3 According to} the experimental procedure of Example 1 of the present invention, a Ga ₂ Se ₃ powder can be prepared.

(5) Preparing the powders of Cu ₂ Se, In ₂ Se ₃ and Ga ₂ Se ₃ according to the required molar ratio, and then holding the mixed powder at a temperature of 700 ° C for one hour under a protective gas. It can be burned into CIGSe powder. As shown in Fig. 12~14, the diffraction analysis of the X-ray structure confirmed that there was no miscellaneous, and it was supplemented by the analysis of the scanning electron microscope image and the optical image.

Example 3 CuGa alloy powder preparation:

(1) The gram weight required for Cu and Ga is calculated from the Moby ratio of the CuGa alloy powder.

(2) The gallium ingot and the copper powder are mixed by the pre-processing method described in the first section.

(3) The powder of the liquid gallium-coated copper powder uniformly mixed is subjected to a protective gas, and the CuGa alloy powder can be prepared by holding the temperature at 700 ° C for two hours in a one-stage simmering manner. As shown in Figures 15 to 17, the diffraction analysis of the X-ray structure confirmed that there was no miscellaneous existence, and was supplemented by the analysis of the scanning electron microscope image and the optical image.

Example 4 GaP compound powder preparation:

(1) The GaP compound powder calculates the grammage required for P and Ga in accordance with 1:1 Mo ratio.

(2) The gallium ingot and the phosphor powder are mixed by the pre-processing method described in the first section.

(3) The powder of the liquid gallium-coated phosphor powder uniformly mixed is subjected to a two-stage calcination method at a temperature of 300 ° C for one hour and a temperature of 700 ° C for one hour to prepare a GaP compound powder. As shown in Fig. 18~20, the diffraction analysis of the X-ray structure confirmed that there was no miscellaneous, and it was supplemented by the analysis of the scanning electron microscope image and the optical image.

Example 5 Preparation of Mg-Ga Mesometallic Powder:

(1) The Mg-Ga intermetallic powder calculates the grammage required for Mg and Ga in accordance with 1:1 Mo ratio.

(2) Mixing the gallium ingot and the magnesium powder by the pre-processing method described in the first section.

(3) The powder of the gallium-coated copper powder uniformly mixed is prepared by a two-stage protective gas simmering method at a temperature of 300 ° C for one hour and a temperature of one hour at 600 ° C to prepare a MgGa intermetallic powder. The Mg+Ga ₂ Mg secondary phase remaining in the reaction is incomplete, and Mg+Ga ₂ Mg → 2GaMg can be reacted by increasing the reaction temperature. As shown in Fig. 21~23, the X-ray structure diffraction analysis confirmed that there is no miscellaneous existence, and supplemented by the analysis of the scanning electron microscope image and optical image.

Example Six Ga ₂ O ₃ Powder Preparation:

(1) The grammage of the Ga ₂ O ₃ powder required to extract the appropriate Ga by the desired gallium oxide.

(2) The gallium ingot and the carbon powder are mixed by the pre-operation processing method described in the first part, and the required carbon powder is a sacrificial type powder, and the amount thereof is not limited, and only needs to be sufficiently mixed with the liquid gallium.

(3) The powder of the liquid gallium-encapsulated carbon powder uniformly mixed is placed in the air, and the Ga ₂ O ₃ powder can be prepared by holding the temperature at 800 ° C for two hours in a one-stage calcination method. As shown in Fig. 24~26, the diffraction analysis of the X-ray structure confirmed that there was no miscellaneous, and it was supplemented by the analysis of the scanning electron microscope image and the optical image.

Example 7 GaN powder preparation:

(1) This powder requires gallium to be mixed and adsorbed with nitrogen by scraper shear technology, but nitrogen is not solid, but it is not possible to use sacrificial powder, such as carbon black powder, to coat Ga because of the carbon black that is coated. Cannot be separated from synthetic GaN powder.

(2) 0.5 g of purchased GaN powder is taken to scrape Ga to adhere Ga to the outside of the GaN powder, and then the Ga-GaN mixed powder is subjected to a reaction temperature of 850 ° C for 1 hour under a NH ₃ atmosphere to react. All are powders of GaN.

(3) Analysis of the powder obtained after the reaction, as shown in Fig. 27 to 29, respectively, was confirmed by X-ray structure diffraction analysis, and no miscellaneous presence was observed, and the analysis of the scanning electron microscope image and the optical image was supplemented.

(4) Using the expensively purchased GaN powder through the GaN powder obtained in the step (2), it is possible to continue to adsorb Ga by a coating technique, and then to produce a GaN powder. Using this iterative step will result in a small amount of expensive purchased GaN powder being converted into a large amount of self-made inexpensive GaN powder.

(1). . . CIGSe: Copper indium gallium selenide

(2). . . GaAs: gallium arsenide

(3). . . GaN: gallium nitride

(4). . . AlGaInP: aluminum gallium indium phosphide

(5). . . InGaN: Indium Gallium Nitride

(6). . . AlGaAs: aluminum gallium arsenide

(7). . . AlGaP: aluminum gallium phosphide

(8). . . CuGa: copper gallium alloy

(9). . . GaP: gallium phosphide

(10). . . Ga ₂ Se ₃ : gallium selenide

(11). . . MgGa: magnesium gallium intermetallic compound

(12). . . Ga ₂ O ₃ : gallium oxide

(13). . . SEM: Scanning Electron Microscope

(14). . . XRD: X-ray structure diffraction analysis

Figure 1. After the gallium ingot is liquefied into a bead shape (liquid form) and the scraper is indicated

Figure II. A schematic diagram of liquid gallium being spread onto a substrate after being subjected to shear stress by a doctor blade

Figure III. Unfolded liquid gallium, elemental powder to be reacted, and substrate diagram above 30 °C

Figure IV. Schematic diagram of the action of the elemental powder to be reacted to the expanded liquid gallium process

Figure V. Schematic diagram of the interaction between the elemental powder to be reacted and liquid gallium after the scraper continues to apply shear stress for a period of time.

Figure VI. Schematic diagram of the elemental powder to be reacted and the liquid gallium are thoroughly mixed.

Figure VII. Schematic diagram of placing a uniformly mixed powder in a glass jar

Figure VIII. Schematic diagram of high temperature atmosphere tubular furnace (annealing furnace)

Figure IX. XRD Analysis of Powders of Ga ₂ Se ₃ Compounds

Figure X. SEM Analysis of Ga ₂ Se ₃ Compound Powder

Figure XI. Physical photo of Ga ₂ Se ₃ compound powder

Figure XII. XRD analysis of CIGSe

Figure XIII. SEM analysis of CIGSe powder

Figure XIV. CIGSe powder solid optical photo

Figure fifteen. XRD Analysis of CuGa Alloy Powders

Figure XVI. SEM Analysis of CuGa Alloy Powder

Figure 17. Solid optical photo of CuGa alloy powder

Figure 18. XRD Analysis of GaP Compound Powders

Figure XIX. SEM analysis of GaP compound powder

Figure twenty. GaP compound powder physical optical photo

Figure twenty one. XRD Analysis of Mg-Ga Intermetallic Powders

Figure twenty-two. SEM analysis of Mg-Ga intermetallic powder

Figure twenty-three. Solid optical photo of Mg-Ga intermetallic powder

Figure twenty-four. XRD Analysis of Ga ₂ O ₃ Powder

Figure twenty-fif. SEM analysis of Ga ₂ O ₃ powder

Figure twenty-six. Ga ₂ O ₃ powder solid optical photo

Figure twenty-seven. XRD Analysis of GaN Powders

Figure twenty eight. SEM analysis of GaN powder

Figure twenty-nine. GaN powder solid optical photo

Claims (7)

A method for preparing a gallium-containing powder, which can synthesize gallium selenide (Ga ₂ Se ₃ ), copper indium gallium selenide (Cu(In,Ga)Se ₂ ), copper gallium alloy (CuGa), gallium phosphide (GaP) , magnesium gallium (GaMg) mesometallic compound, gallium oxide (Ga ₂ O ₃ ), gallium nitride (GaN) and other kinds of gallium-containing powder, the powder represents GaX powder X in the following form: more than one powder state Material, covered metal, non-metallic element, alloy or compound. The method for fabricating the gallium-containing powder comprises the steps of: (1) providing a substrate for heating and a doctor blade; (2) unrolling the Ga metal on the substrate by using a doctor blade; and (3) spreading other powders (Se, Cu, P) , Mg, carbon black, GaN, etc.), using a doctor blade to repeatedly mix back and forth, so that other powders are coated and wrapped with Ga metal until the Ga metal unfolded on the substrate is completely removed, and other powders contaminated with Ga metal are obtained. (a) step (3) to obtain a Fe powder coated with Ga metal, represented by Ga / Se; (b) step (3) to obtain a Cu powder coated with Ga metal, represented by Ga / Cu; (c) Step (3) to obtain a P powder contaminated with Ga metal, represented by Ga/P; (d) Step (3) to obtain Mg powder coated with Ga metal, represented by Ga/Mg; Step (3) to obtain a carbon black powder coated with Ga metal, represented by Ga/carbon black; (f) Step (3) to obtain a GaN powder coated with Ga metal, represented by Ga/GaN; (4) The powder obtained in the step (3) is heated in a high temperature atmosphere reaction furnace; (5) holding temperature; (6) cooling; (7) ball milling to refine and homogenize the particle size. The powders such as Ga/Se, Ga/Cu, Ga/P, and Ga/Mg obtained in the second item of the patent application are reacted at 200-800 ° C in a protective gas atmosphere to obtain gallium selenide (Ga ₂ Se ₃ ), Different powders such as CuGa, GaP, and GaMg. The Ga/carbon black powder obtained in the second item of the patent application is reacted at 800 ° C with an air atmosphere to obtain a gallium oxide (Ga ₂ O ₃ ) powder. The Ga/GaN powder obtained in the second item of the patent application is subjected to an amination reaction at a temperature of 800 ° C or higher and an NH ₃ atmosphere to obtain an enlarged gallium oxide (GaN) powder. The gallium selenide (Ga ₂ Se ₃ ) powder obtained in the second application of the patent application is mixed with Cu ₂ Se and In ₂ Se ₃ powder obtained by the conventional powder method, and then reacted at 700 ° C to obtain Cu (In , Ga) Se ₂ powder. The reaction temperature carried out in items 3, 4, 5 and 6 of the patent application range is 200-1000 ° C, and the holding time is half an hour to 3 hours.