Effect of pressure on the properties of phosphorus-doped p-type ZnO thin films grown by radio frequency-magnetron sputtering

We report the effect of pressure on the surface morphology, electrical and optical properties of phosphorus (P)-doped p-type ZnO grown by radio frequency magnetron sputtering. The nanorod structures of P-doped ZnO films became dense and flat with decreasing pressure. The Hall effect measurement of the films grown at a pressure of 5–20mTorr showed an n-type conductivity after rapid thermal annealing. However, the films grown at a low pressure of 1mTorr showed a p-type conductivity with a hole concentration of 4.71×1818∕cm3. This result showed that the pressure of rf-magnetron sputtering plays a critical role in the growth of P-doped p-type ZnO.