Optical performance of europium-doped β gallium oxide PVD thin films

Abstract

β-Gallium oxide is a wide bandgap material that is used in many electronic devices owing to its ultra wide bandgap of ~ 5 eV. It is commonly doped with rare earth metals like europium to improve its electronic and photoluminescence properties. However, the effect of doping concentration on particularly the optical properties has not been clearly reported yet. Here the aim was to dope β gallium oxide with different concentrations of europium. Therefore europium and gallium oxide were co-sputtered to get varying concentrations of europium in β gallium oxide structure. The doping concentration varied from 4.6 to 10.1 mole% of europium. Their microstructure and phase was studied by SEM and XRD, respectively and their optical performance was studied using UV–Vis spectrophotometer. The optical bandgap of β gallium oxide was found to decrease due to doping with europium. Although the transmittance increased drastically with increase in doping concentration from 4.6 to 10.1%, their bandgap was independent of the dopant concentration. In consultation with the binary phase diagram and photoluminescence of the thin films, the optimal dopant concentration in β gallium oxide was found to be around 10% Eu.