Nitrogen and aluminum codoped p-type ZnO films and ZnO p-n homojunctions

The most significant impediment to the widespread exploitation of ZnO-related materials in electronic and photonic applications is the difficulty in p-type doping and synthesizing ZnO p-n homojunctions. To resolve the problem of p-type doping in ZnO, nitrogen and aluminum (N-Al) codoped ZnO films were prepared by ultrasonic spray pyrolysis technique. The structural, optical and electrical properties of the as-grown ZnO films were investigated by X-ray diffraction (XRD), photoluminescence (PL) spectra, Hall-effect and Seebeck-effect measurements. The results demonstrate that the N-Al codoped ZnO films show extremely excellent p-type conduction and good ultraviolet emission characteristics. Furthermore, ZnO homojunctions were synthesized by depositing the undoped ZnO layers on the N-Al codoped ZnO layers, and the current-voltage (I-V) characteristics measured from the two-layer structure show a typical rectifying characteristics of p-n junctions with a low turn-on voltage of about 2.5 V.