Bandgap bowing parameter and alloy fluctuations for β-(AlxGa1?x)2O3 alloys for x ≤ 0.35 determined from low temperature optical reflectivity

摘要

A bandgap bowing parameter of 0.4 ± 0.2?eV for β-(Al x Ga 1? 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 β-(Al x Ga 1? x ) 2 O 3 alloys. The unit cell of β-(Al x Ga 1? 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 β-(Al x Ga 1? x ) 2 O 3 alloys, which are an important material system for applications in deep ultraviolet opto-electronic devices.