TEMPERATURE-DEPENDENT PHOTOLUMINESCENCE STUDIES OF ZNSE-I SINGLE-CRYSTALS GROWN BY CHEMICAL-VAPOR TRANSPORT

The single crystal ZnSe:I sample was grown by the chemical vapor trans port (CVT) method using iodine as the transporting agent. The iodine i ncorporates itself effectively as a donor in the lattice. The sample s hows a [Ill] optical quality surface and has an absorption edge at 2.5 5 eV due to a deep impurity band nearly 0.15 eV below the conduction b and. The photoluminescence emission spectra of this crystal have been measured for its temperature dependence as well as for excitation ener gy dependence. The photoluminescence is in accordance with a donor-acc eptor complex formation involving iodine activated donors and self-act ivated accepters. The configuration coordinate model has been used to explain the temperature dependent changes in the peak position and the bandwidth of the emission band. The decrease in luminescence efficien cy with increasing temperature is explained by using a simple model fo r thermal quenching. The activation energy at low temperature range (T < 200 K) is different from that at high temperature range (200 K < T < 300 K).