Tb-doped β-(AlxGa1-x)2O3 epitaxial films on c-sapphire substrates fabricated via a spin-coating method

Abstract

β-(AlxGa1-x)2O3 epitaxial films are wide-bandgap semiconductors that may be used to fabricate next-generation optoelectronic and high-power devices. In this study, we demonstrate the dual effects of rare-earth doping and bandgap engineering on the structural, chemical, and optical properties of terbium (Tb)-doped β-(AlxGa1-x)2O3 epitaxial films prepared on c-sapphire substrates using an inexpensive sol-gel spin-coating deposition method. The (2¯01)-oriented epitaxial films prepared with Al at concentrations (x) of 0.3, 0.5, and 0.7 exhibit bandgap energies of 4.92, 5.31, and 5.84 eV, respectively. Photoluminescence spectroscopy analysis revealed two types of emission bands with each originating from a different luminescence center. The emission bands captured in the 300–500 nm wavelength range (UV, blue, and green) resulted from intrinsic defects in the recombination processes in the host material, whereas the emissions in the 500–800 nm range could be assigned to radiative emissions from the Tb dopant. Collectively, the results of this study demonstrate the effectiveness of a simple solution deposition approach that can be used to fabricate novel materials and compositions with tunable properties for a broad range of potential applications.