DLTS EVALUATION OF NONEXPONENTIAL TRANSIENTS OF DEFECT LEVELS IN CUPROUS-OXIDE (CU2O)

The DLTS nonexponential transients of the Schottky barrier CU/Cu2O are investigated. The DLTS spectra are due to acceptor states distributed in energy and their origin is attributed to structural anomalies and ''islands'' of CuO in the material. The analysis, based on a weak disordered Gaussian distribution of the acceptor states, gives real values of the activation energy E0 and the capture cross section, which are smaller than the ones determined from standard DLTS analysis. A small deviation from the Gaussian distribution was observed for temperatures higher than the one corresponding to the peak of the DLTS signal. This is attributed to a small assymetry of the trap-band distribution with respect to the maximum of the trap-band. The maximum concentration of the trap-band distribution is located above the Fermi level. The above observations are true only for a sample which was annealed at 500-degrees-C in air. The assymetry of the trap-band distribution is quite large for a sample annealed at 400-degrees-C. First results are presented and the need for a new model is emphasized for this case.