Donor and acceptor competitions in phosphorus-doped ZnO

Abstract

Phosphorus-doped ZnO films were grown by molecular-beam epitaxy with a GaP effusion cell as dopant source. Three growth regions were identified to obtain ZnO films with different conduction types. In the oxygen-extremely-rich region, phosphorus-doped ZnO films show n-type conduction with dominant donor-bound excitons (DX0) in the low-temperature photoluminescence (PL) spectra. In the oxygen-rich region, a growth window was found to generate p-type ZnO films. The PL spectra show evident competitions between DX0 and acceptor-bound excitons (AX0). In the stoichiometric and Zn-rich region, ZnO films are n-type with dominant DX0 emissions. Thus, phosphorus doping is amphoteric, having the tendency to form both donors and acceptors in ZnO.