Photoluminescence Studies of Semiconducting Polycrystalline CdTe Films

We report the first systematic measurements of the temperature dependence of the photoluminescence (PL) in the range of 10–300 K in CdTe. The experiments were carried out on semiconducting CdTe films of high quality grown by a modified close-spaced vapour transport (CSVT) technique. Several luminescence bands were observed, one around 1.4 eV showing a temperature-independent behaviour, and another band located around 1.52 eV, at 300 K, showing a strong temperature dependence. The excitonic origin of this band at low temperatures has been confirmed by the dependence of the PL intensity on the excitation intensity. A band-to-band luminescent recombination component at high temperatures is also observed. This study allows us to elucidate the nature and basic physical properties of the bound exciton as well as the temperature dependence of the band gap.