The photoluminescence spectra of As doped p-type ZnO thin films reveal neutral acceptor bound exciton of 3.3437 eV and a transition between free electrons and acceptor levels of 3.2924 eV. Calculated acceptor binding energy is about 0.1455 eV. Thermal activation and doping mechanism of this film have been suggested by the analysis of x-ray photoelectron spectroscopy. p-type formation mechanism of As doped ZnO thin film is related to the AsZn–2VZn complex model. ZnO-based p-n junction was fabricated by the deposition of an undoped n-type ZnO layer on an As doped p-type ZnO layer.