title: Theoretical and experimental investigation of optical absorption anisotropy in β-Ga2O3.
abstract: The question of optical bandgap anisotropy in the monoclinic semiconductor β-Ga2O3 was revisited by combining accurate optical absorption measurements with theoretical analysis, performed using different advanced computation methods. As expected, the bandgap edge of bulk β-Ga2O3 was found to be a function of light polarization and crystal orientation, with the lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6 eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The theoretical analysis clearly indicates that the shift in the b onset is due to a suppression of the transition matrix elements of the three top valence bands at Γ point.
authors.affiliation: Department of Physics, University of Cagliari, Cittadella Universitaria, 09042 Monserrato (CA), Italy.
authors.forename: F
authors.initials: F
authors.lastname: Ricci
authors.forename: F
authors.initials: F
authors.lastname: Boschi
authors.forename: A
authors.initials: A
authors.lastname: Baraldi
authors.forename: A
authors.initials: A
authors.lastname: Filippetti
authors.forename: M
authors.initials: M
authors.lastname: Higashiwaki
authors.forename: A
authors.initials: A
authors.lastname: Kuramata
authors.forename: V
authors.initials: V
authors.lastname: Fiorentini
authors.forename: R
authors.initials: R
authors.lastname: Fornari