Bandgap Bowing Parameter And Alloy Fluctuations For Beta-(Alxga1-X)(2)O-3 Alloys For X <= 0.35 Determined From Low Temperature Optical Reflectivity

A bandgap bowing parameter of 0.4 +/- 0.2 eV for beta-(AlxGa1-x)(2)O-3 alloys, with Al compositions (x) up to 0.35, has been determined from the bandgap obtained from low temperature optical reflectivity, which suppresses the effect of electron-phonon interaction on the bandgap. A length scale of inhomogeneity of 0.21 +/- 0.03 times of the electron-hole mean free path length has been estimated for beta-(AlxGa1-x)(2)O-3 alloys. The unit cell of beta-(AlxGa1-x)(2)O-3 alloys compresses, and the lattice parameters vary linearly with Al substitution. Our results provide insight into bandgap engineering and alloy disorder for beta-(AlxGa1-x)(2)O-3 alloys, which are an important material system for applications in deep ultraviolet opto-electronic devices. (c) 2021 Author(s).