LiGaO2 single crystal as a lattice-matched substrate for hexagonal GaN thin films

Abstract

The thermal expansion coefficient of a nearly lattice-matched substrate LiGaO2 was investigated by dilatometry and the thermal expansion coefficients on the LiGaO2 (001) plane are 11.0×10−6/K along the [010] axis and 1.7×10−6/K along the [100] axis. The strong anisotropy leads us to conclude that both the compressive and tensile strains are induced in the GaN thin film grown on the (001) LiGaO2 substrate. The growth features of the GaN thin film were different on each side of the LiGaO2 substrate with a single domain. The results suggest that both lattice matching and polarity play an important role in the GaN epitaxial growth on the LiGaO2 substrate.