【World Express】For the First Time in the World, the Physical Properties of Ga₂O₃ Melt were Successfully Measured on the International Space Station, Further Accelerating the Practical Application of Ga₂O₃ Wafers

  For the first time, AGC (president（CEO）: Yoshinori Hirai) used the electrostatic levitation furnace (ELF) owned by JAXA (Japan Aerospace Exploration Agency, Director: Hiroshi Yamakawa) on the Japanese experimental module of the International Space Station "Hope" to successfully measure the physical properties of gallium oxide melt--a high melting point material .

  Power semiconductor is an electronic component composed of various electrical and electronic devices, such as servers, automobiles, industrial machinery and household appliances, which controls power. Compared with the existing power semiconductor material silicon, gallium oxide, as the next generation semiconductor material, is attracting great attention due to its great potential of low power consumption and being used under high voltage and large current.

  AGC has always been interested in the promising future of gallium oxide and has been working with NCT since 2018. However, the melting point of gallium oxide is about 1800 ℃, so the traditional method of melting the sample in the crucible (container) will cause impurities to be mixed in the material. This makes it difficult to obtain the melt properties required for numerical simulation during the production of Ga₂O₃ single crystals.

  JAXA's electrostatic suspension furnace suspends the sample under microgravity, and melts it with laser instead of crucible, thus it is possible to obtain highly accurate physical property values of molten liquid of high melting point materials. This experiment was carried out by using the pay system of electrostatic suspension furnace. For the first time in the world, the team successfully obtained the melt physical property values, including  coefficient of viscosity and surface tension, in addition to the melt density of Ga₂O₃ at melting point and in a wide range of temperatures. In the future, this data will be used for numerical simulation to accelerate the development of higher quality and larger size Ga₂O₃ single crystal substrate technology, and further improve the output in the production process. The results was announced at the 69th Spring Meeting of the Japanese Society of Applied Physics in 2022.