Photocurrent study of the valence band splitting of AgInS2 epilayers on GaAs

AgInS2 epilayers have been grown on a GaAs substrate by using the hot-wall epitaxy method. The temperature dependence of the band gap energy of AgInS2 is determined to be E g (T)=2.1365 eV −(9.89×10 −3 eV )T 2 /(2930+T) using the absorption spectra. The free exciton binding energy, Δcr, and Δso of the chalcopyrite AgInS2 have been found to be 0.1115, 0.1541, and 0.0129 eV, respectively. This result reveals that the Δso splitting clearly exists for the Γ5 states of the valence band in the AgInS2 epilayer.