N-doped and Zr–N codoped p-type ZnO films were grown on sapphire substrates by pulsed laser deposition. The carrier type and conduction are very sensitive to N2O deposition pressure. p-type conduction is observed only for films grown at an intermediate pressure range (5×10-5–5×10-4 Torr). The Zr–N codoped ZnO films grown at 500 °C in 5×10-5 Torr of N2O show p-type conduction behavior with a low resistivity of 0.026 Ω cm, a carrier concentration of 5.5×1019 cm-3, and a mobility of 4.4 cm2 V-1 s-1. The p-type conduction behavior of Zr–N codoped ZnO films is also confirmed by the rectifying I-V characteristics of p-n heterojunctions (p-ZnO/n-Si).