Structural and electrical properties of Al and P co-doped ZnO thin films prepared by pulsed laser deposition

In this work, Al and P were co-doped in ZnO and the electrical properties of the thin films as functions of the Al/P ratios and oxygen partial pressure were investigated. The thin films were grown on sapphire substrates by the pulsed laser deposition method. The crystal structure of the thin films was found to have a polycrystalline hexagonal wurtzite structure with a c-axis preferred orientation. The depth profiles of the SIMS showed that more P is soluble and more Zn vacancy is formed as the oxygen partial pressure increased, which is favorable for hole generation. In the case of the films with Al/P ratios of 1 and 1/2, the n-type conductive electrical characteristic was changed to p-type as the oxygen partial pressure increased.