The fundamental absorption edge in MnIn2Se4 layer semi-magnetic semiconductor

Abstract

From the study of the optical absorption coefficient and photoluminescence spectra of the layer semi-magnetic semiconductor MnIn2Se4 the nature of its fundamental absorption edge is established. It is found that the lowest-energy-gap of this compound is allowed-indirect between parabolic bands that vary from about 1.55–1.43eV in the temperature range from 10K to room temperature. In addition, two allowed direct band-to-band transitions beginning at 1.72 and 1.85eV at 295K, and at 1.82 and 1.96eV at 10K which are related to optical absorption processes between the uppermost Γ4(z) and the middle Γ5(x) valence bands and the conduction band respectively, are observed in the high energy range. It is also found that the crystal field splitting parameter (Δcf) of MnIn2Se4 is of about 0.15eV nearly independent of the temperature. At energies around 2.2eVa photoluminescence band related to internal transitions between d-excited levels of Mn+2 ion to its 6A1 ground state is also observed in spectra.