Modulation of electronic and optical properties by surface vacancies in low-dimensional β-Ga2O3.

Calculations using the Heyd-Scuseria-Ernzerhof screened hybrid functional reveal the detailed influence that surface vacancies have on the electronic and optical properties of low-dimensional (LD) β-Ga2O3. Vacancies manifest subtle changes to the electronic characteristics as oxygen states predominate the valence band at the surface. Dielectric functions at the surface are found to increase with vacancies and defects. A broad impact on optical properties, such as absorption coefficients, reflectivity, refractive indices, and electron loss, is seen with increased vacancy defects. Both visible and infrared regions show direct correlation with vacancies while there is a marked decrease in the deep ultraviolet (UV) region. These calculations on the β-Ga2O3 model system may guide the rational design of two-dimensional optical devices with minimized van der Waals forces.