Ga2O3 is one of wide band gap semiconductors. The features of this material are a large band gap and an easiness of making bulk crystal. Band gap energy is as high as 4.5 – 4.8 eV. N-type conductivity is controlled in a wide carrier concentration range between 1015 -1019 cm-3 by impurity doping using Si or Sn. Very high resistivity of 1012 Ωcm is also realized by Fe or Mg doping. Single crystal substrates up to 4-inch diameter have been already demonstrated. Bulk crystals of Ga2O3 can be made by a melt growth method such as FZ, CZ, and EFG. This enables us to produce low-cost and high-quality substrates. Growth rate of Ga2O3 is more than 10 times higher than that of GaN and SiC whose bulk crystal growth is done from diluted vapor phase.
These great features of this material lead to a possibility of using it for various applications including LEDs and power devices. In the seminar, I’ll introduce the properties of Ga2O3 substrates and the present status of application developments.