Question

Non-stoichiometric cuprous oxide, $C{u}_{2}O$ can be prepared in laboratory. In this oxide, copper to oxygen ratio is slightly less than 2 : 1. Can you account for the fact that this substance is a p - type semicondutor ?

Answer 1

The ratio of copper to oxygen is slightly less than 2 : 1. This shows that some cuprous $\left(C{u}^{+}\right)$ ions have been replaced by cupric $\left(C{u}^{2+}\right)$ ions. In order to maintain the electrical neutrality of the molecule, every two $C{u}^{+}$ ions will be replaced by one $C{u}^{+}$ ion which results in creating cation vacancies leading to positive holes. Since the conduction is due to positive holes, it is a p-type semiconductor.