Thermally stimulated conductivities in CdInGaS4

To investigate the characteristics of traps in a single crystal of CdInGaS4, the thermally stimulated current has been measured in the temperature range from 90 to 300 K by varying the wavelength of light used for excitation. The results are analysed in terms of the discrete-level model first developed by Haering and Adams (1960). On the basis of the slow-retrapping regime, least-squares curve fittings are made to distinguish between trapping levels. Trap energies are obtained as 0.13, 0.15, 0.17 and 0.21 eV for shallow traps and 0.3 eV for deep traps together with other trapping parameters. From the value of the cross sections obtained, all the traps are considered to be associated with repulsive centres.