Optical absorption and photoluminescence in the defect-chalcopyrite-type semiconductorZnIn2Te4

Abstract

Optical absorption and photoluminescence (PL) spectra have been measured on the defect-chalcopyrite-type semiconductor ${\mathrm{ZnIn}}_{2}{\mathrm{Te}}_{4}$ in the 1.1--1.6 eV photon-energy range at temperatures between 11 and 300 K. The temperature dependence of the direct-gap energy of ${\mathrm{ZnIn}}_{2}{\mathrm{Te}}_{4}$ has been determined from the optical absorption spectra and fit using the Varshni equation and an analytical four-parameter expression developed for the explanation of the band-gap shrinkage effect in semiconductors. The PL spectra show an asymmetric emission band at $\ensuremath{\sim}1.4\mathrm{eV},$ which is attributed to donor-acceptor pair recombination between quasicontinuously distributed donor states and acceptor levels. At temperatures above 90 K, the band-to-band emission begins to appear at the high-energy tail of the donor-acceptor pair recombination. A double-exponential fit analysis of the PL spectra suggests an acceptor level of 64 meV and an unidentified shallow level of 9 meV. An energy-band scheme has been proposed for the explanation of PL emission in the defect-chalcopyrite-type semiconductors.