Broad-band photoluminescence of donor–acceptor pairs in tetrahedrite Cu10Cd2Sb4S13 microcrystals

Abstract

We present temperature and laser power dependent photoluminescence (PL) study of Cd substituted tetrahedrite Cu10Cd2Sb4S13 microcrystals. At T = 10 K a single broad, asymmetric and structureless PL band was detected at about 1.08 eV. The temperature and laser power dependencies indicate that the properties of PL emission can be explained by the distant donor–acceptor (DA) pair model, where a donor defect has a depth of E D ≈ 30 meV and an acceptor defect E A = 88 ± 6 meV. It was shown that the shape of the DA pair band could be effectively described using statistical distribution of donor–acceptor defects, recombination probability of DA pairs with different spatial separation, relatively strong electron–phonon coupling and occupation probabilities of donor and acceptor defects. At T = 200 K the DA pair recombination gradually starts to transform into conduction band-acceptor recombination.