Electronic structure and optical properties of noncentrosymmetric LiGaSe 2 : Experimental measurements and DFT band structure calculations

摘要: Abstract We report on measurements of X-ray photoelectron (XP) spectra for pristine and Ar+ ion-irradiated surfaces LiGaSe2 single crystal grown by Bridgman-Stockbarger method. Electronic structure the compound is studied from a theoretical experimental viewpoint. In particular, total partial densities states are investigated density functional theory (DFT) calculations employing augmented plane wave + local orbitals (APW + lo) method they verified data spectroscopy measurements. The DFT indicate that main contributors to valence band Se 4p states, which contribute mainly at top in upper portion band, with also essential contributions these lower band. Other substantial emerge Ga 4s contributing ant portions respectively. With respect conduction its bottom composed unoccupied s p states. present confirmed experimentally when comparing XP valence-band spectrum LiGaS2 common energy scale emission bands representing distribution Measurements fundamental absorption edges room temperature reveal bandgap value, Eg, equal 3.47 eV Eg value increases up 3.66 eV decreasing 80 K. optical characteristics clarified calculations.