Structural and electrical properties of nitrogen and aluminum codoped p-type ZnO films

To resolve the problem of p-type doping in ZnO, nitrogen and aluminum (N–Al) codoped ZnO films were prepared by the ultrasonic spray pyrolysis (USP) technique. The structural and electrical properties of N–Al codoped ZnO films were investigated. The results demonstrate that the undoped ZnO films exhibit the preferential orientation of (002) plane, while ZnO films show high orientation of (101) plane after codoping with N and Al. The N–Al codoped ZnO films under optimum conditions show p-type conduction, with a low resistivity of 1.7×10−2Ω cm, carrier concentration of 5.09×1018 cm−3 and high Hall mobility of 73.6 cm2 V−1 s−1. A conversion from p-type conduction to n-type was observed during the increase of measurement temperature.