Epitaxial growth of κ- and γ-Ga₂O₃ thin films with alloying and lattice matching

Abstract

Gallium oxide (Ga₂O₃) has a large bandgap (approx. 5.0 eV) and exhibits an excellent potential for power-switching and deep-ultraviolet optoelectronic devices. Ga₂O₃ possesses five polymorphs, namely α-, β-, γ-, δ-, and κ-phases. In this article, among the five polymorphs, we introduce the epitaxial growth of γ- and κ-phase Ga₂O₃. The κ-Ga₂O₃ exhibits a ferroelectric property and a large spontaneous polarization. The γ-Ga₂O₃ with the incorporation of Al₂O₃ is lattice-matched to a spinel substrate and exhibits a large bandgap of 5.8 eV. The results of the epitaxial growth of κ- and γ-Ga₂O₃ thin films by mist CVD are discussed, focusing on lattice matching and alloying.