Non-stoichiometric cuprous oxide, ${{Cu}_{2}}$O can be,
prepared in the 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 semiconductor?
The ratio is less than 2:1, in ${{Cu}_{2}}$O which shows that
some cuprous, ${{Cu}^{+}}$ ions have been replaced by cupric, ${{Cu}^{2+}}$ ions. Thus, the maintain electrical neutrality, every two ${{Cu}^{+}}$ ions will be replaced by one ${{Cu}^{2+}}$ion, therefore creating a hole. As conduction is due to the presence of positive holes, hence it is p-type semiconductor.