Abstract: A method of increasing the resistivity of a silicon carbide wafer includes providing a silicon carbide wafer with a first resistivity, and applying a microwave to treat the silicon carbide wafer. The treated silicon carbide wafer has a second resistivity. The second resistivity is higher than the first resistivity. The microwave treated silicon carbide wafer can be applied in a high-frequency device.

Abstract: A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000° C. to 1600° C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

Abstract: A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000° C. to 1600° C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

Abstract: A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000° C. to 1600° C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

Abstract: A method of purifying silicon carbide powder includes: providing a container with a surface coated by a nitrogen-removal metal layer, wherein the nitrogen-removal metal layer is tantalum, niobium, tungsten, or a combination thereof; putting a silicon carbide powder into the container to contact the nitrogen-removal metal layer; and heating the silicon carbide powder under an inert gas at a pressure of 400 torr to 760 torr at 1700° C. to 2300° C. for 2 to 10 hours, thereby reducing the nitrogen content of the silicon carbide powder.

Abstract: A method of purifying silicon carbide powder includes: providing a container with a surface coated by a nitrogen-removal metal layer, wherein the nitrogen-removal metal layer is tantalum, niobium, tungsten, or a combination thereof; putting a silicon carbide powder into the container to contact the nitrogen-removal metal layer; and heating the silicon carbide powder under an inert gas at a pressure of 400 torr to 760 torr at 1700° C. to 2300° C. for 2 to 10 hours, thereby reducing the nitrogen content of the silicon carbide powder.

Abstract: A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000° C. to 1600° C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

Abstract: A method for manufacturing micropowder is provided, which includes (a) mixing a silicon precursor and a carbon precursor to form a mixture, and heating and keeping the mixture at 1600° C. to 1800° C. under a vacuum and non-oxygen condition for 120 to 180 minutes to form a silicon carbide powder; and (b) heating and keeping the silicon carbide powder at 1900° C. to 2100° C. under non-oxygen condition for 5 to 15 minutes, and then cooling and keeping the silicon carbide powder at 1800° C. to 2000° C. under the non-oxygen condition for 5 to 15 minutes to form micropowder, wherein the micropowder includes a silicon carbide core covered by a carbon film.

Abstract: A method for manufacturing micropowder is provided, which includes (a) mixing a silicon precursor and a carbon precursor to form a mixture, and heating and keeping the mixture at 1600° C. to 1800° C. under a vacuum and non-oxygen condition for 120 to 180 minutes to form a silicon carbide powder; and (b) heating and keeping the silicon carbide powder at 1900° C. to 2100° C. under non-oxygen condition for 5 to 15 minutes, and then cooling and keeping the silicon carbide powder at 1800° C. to 2000° C. under the non-oxygen condition for 5 to 15 minutes to form micropowder, wherein the micropowder includes a silicon carbide core covered by a carbon film.

Abstract: A method for manufacturing micropowder is provided, which includes (a) mixing a silicon precursor and a carbon precursor to form a mixture, and heating and keeping the mixture at 1600° C. to 1800° C. under a vacuum and non-oxygen condition for 120 to 180 minutes to form a silicon carbide powder; and (b) heating and keeping the silicon carbide powder at 1900° C. to 2100° C. under non-oxygen condition for 5 to 15 minutes, and then cooling and keeping the silicon carbide powder at 1800° C. to 2000° C. under the non-oxygen condition for 5 to 15 minutes to form micropowder, wherein the micropowder includes a silicon carbide core covered by a carbon film.

Abstract: A method for manufacturing micropowder is provided, which includes (a) mixing a silicon precursor and a carbon precursor to form a mixture, and heating and keeping the mixture at 1600° C. to 1800° C. under a vacuum and non-oxygen condition for 120 to 180 minutes to form a silicon carbide powder; and (b) heating and keeping the silicon carbide powder at 1900° C. to 2100° C. under non-oxygen condition for 5 to 15 minutes, and then cooling and keeping the silicon carbide powder at 1800° C. to 2000° C. under the non-oxygen condition for 5 to 15 minutes to form micropowder, wherein the micropowder includes a silicon carbide core covered by a carbon film.