1.4 EV PHOTOLUMINESCENCE IN CHLORINE-DOPED POLYCRYSTALLINE CDTE WITH A HIGH-DENSITY OF DEFECTS

The 1.4 eV photoluminescence (PL) band in a polycrystalline CdTe:CI wi th a high density of defects was studied as a function of the chlorine dopant concentration and temperature. For a material with a high dens ity of defects this band has a smooth, non-symmetrical shape without a ny apparent phonon structure. The energy of the intensity maximum of t he 1.4 eV band depends on the concentration of chlorine and varies fro m 1.389 to 1.408 eV. The temperature quenching of the PL intensity for all samples was measured and the activation energy (ET) was found. Mi nimum and maximum values of the ET were 0.10 and 0.20 eV, respectively . A configurational-coordinate model is proposed for the 1.4 eV PL ban d in which the excited state of the recombination centre lies within t he conduction band. In this model the temperature quenching of the PL is pictured as being essentially due to an electronic transition from the excited state directly to the ground state (the internal mechanism ).