Thermostimulated impurity conduction in characterization of electrodeposited Cu2O films

Abstract

Electrodeposited films of cuprous oxide show high resistivities in the range of 10⁹–10¹² Ω cm. The p‐type conductivity, its temperature dependence, and its thermostimulated characteristics can be explained by assuming that a pair of deep levels (acceptor 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 5×10¹³ cm⁻³ and a hole capture cross section of 3.12×10⁻⁹ cm², this level is compensated with a donor‐type level of unknown ionization energy having a concentration of 1.89×10¹³ 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.