Optical Absorption and Photoluminescence in Defect-Stannite-Type Semiconductor ZnGa<sub>2</sub>Se<sub>4</sub>

Abstract

Optical absorption and photoluminescence (PL) spectra were measured on defect-stannite-type semiconductor ZnGa2Se4 at temperatures T from 11 to 300 K. The square of the absorption coefficient spectra showed distinct two absorption edges, which were E0A,B and E0C,D transitions at Γ point in the Brillouin zone. The temperature dependence of the direct-gap energies, E0A,B and E0C,D, of ZnGa2Se4 were determined and fit using the analytical four-parameter expression developed for the explanation of the band-gap shrinkage effect in semiconductors. The PL emissions at near band-edge and at higher energy than band-edge were also observed at T ≤ 150 K.