We can now consider weakly p-type growth conditions, shown in Figure . Immediately we notice a difference, with the low energy p-type defects from the previous plot moving up in energy, and n-type defects such as the phosphorus vacancy (V P , violet) dropping in energy. However, the lowest energy defect both at the valence band and across all Fermi levels is still V Cu , indicating that even under P-poor, metal rich conditions CaCuP is expected to have reasonably good p-type conductivity. Indeed, we see the best conductivity in P-poor films (Figure ).