Effects of Cu, Zn Doping on the Structural, Electronic, and Optical Properties of alpha-Ga2O3: First-Principles Calculations

The intrinsic n-type conduction in Gallium oxides (Ga2O3) seriously hinders its potential optoelectronic applications. Pursuing p-type conductivity is of longstanding research interest for Ga2O3, where the Cu- and Zn-dopants serve as promising candidates in monoclinic beta-Ga2O3. However, the theoretical band structure calculations of Cu- and Zn-doped in the allotrope alpha-Ga2O3 phase are rare, which is of focus in the present study based on first-principles density functional theory calculations with the Perdew-Burke-Ernzerhof functional under the generalized gradient approximation. Our results unfold the predominant Cu1+ and Zn2+ oxidation states as well as the type and locations of impurity bands that promote the p-type conductivity therein. Furthermore, the optical calculations of absorption coefficients demonstrate that foreign Cu and Zn dopants induce the migration of ultraviolet light to the visible-infrared region, which can be associated with the induced impurity 3d orbitals of Cu- and Zn-doped alpha-Ga2O3 near the Fermi level observed from electronic structure. Our work may provide theoretical guidance for designing p-type conductivity and innovative alpha-Ga2O3-based optoelectronic devices.