Electronic states of gallium oxide epitaxial thin films and related atomic arrangement

Abstract

Amorphous, crystallized, and Mg-doped β-Ga2O3 thin films are investigated to understand the evolution of electronic states and the related atomic arrangement. In the process from the amorphous to crystallized phase of Ga2O3 films, disordered atoms transform into six-fold GaO6 octahedra. The denser structure creates more electron density. The crystallized phase widens the band gap, because of the conduction band changes attributed to the Ga 4s states hybridized with O 2s states. The Mg dopants create four-fold GaO4 tetrahedron deficiency. Moreover, the distances between Ga atoms become shorter for the doped film; however, the Ga–O distance is independent of the dopant. Mg dopants affect the oxygen states in valence band and Ga–O interaction at conduction band, which results in a slightly smaller band gap. The electronic evolution of the amorphous, crystallized and doped films is confirmed by the calculated density of states results. These results will be beneficial for the design of more effective semiconductive films.