Optical and photoelectric properties of monoclinic Zn1 − x Cd x As2 crystals

Abstract

The first data are presented on the band structure of monoclinic Zn1 − xCdxAs2 crystals. The fundamental absorption edge of Zn1 − xCdxAs2 for the E ‖ c polarization is shown to be dominated by an indirect allowed transition for absorption coefficients α‖ 6 cm−1, both transitions involving excitonic levels. The absorption edge for E ⊥ c is due to a direct forbidden transition with the participation of excitonic levels. We have determined the band gap values for these transitions in the temperature range 80–300 K, the exciton binding energy, and the ionization energies of four deep acceptor levels produced in the band gap by structural defects.