THERMOSTIMULATED IMPURITY CONDUCTION IN CHARACTERIZATION OF ELECTRODEPOSITED CU2O FILMS

Electrodeposited films of cuprous oxide show high resistivities in the range of 10(9)-10(12) OMEGA cm. The p-type conductivity, its temperature dependence, and its thermostimulated characteristics can be explained by assuming that a pair of deep levels (aceptor and donor type) control the electrical properties of these films. A novel thermostimulated conductivity model is introduced to include the effect of impurity conduction. Impurity conduction through the acceptor-type level is the dominant transport mechanism at temperatures below approximately 200 K. The experimental results on thermostimulated conductivity measurements reveal the effect of Poole-Frenkel lowering of the ionization energy of the acceptor-type deep level. For a typical sample the zero-field ionization energy of this level is 0.792 eV. Having a concentration of 5 x 10(13) cm-3 and a hole capture cross section of 3.12 x 10(-9) cm2, this level is compensated with a donor-type level of unknown ionization energy having a concentration of 1.89 x 10(13) cm-3. Impurity conduction in this sample shows an activation energy of 0.03 eV before and 0.08 eV after a sample is illuminated at 77 K. From the measurement of the Poole-Frenkel constant the electron affinity of the film is obtained to be 2.9 eV.