p-Type Formation Mechanism of Codoped and Tridoped ZnO Thin Films

The p-type formation mechanism of codoped (Al-As) and tridoped (Al-As-N) ZnO thin films grown by RF sputtering has been reported. The codoped and tridoped ZnO films have been achieved through As back diffusion from GaAs substrate with Al2O3 and AlN mixed ZnO targets, respectively. The p-conductivity of the films has been confirmed by Hall effect measurements. The lowest room temperature resistivity of similar to 10(-2) Omega cm has been obtained by both methods. The diffusion of As atoms and presence of dopants in the films have been confirmed by time of flight-secondary ion mass spectrometry analysis. X-ray photoelectron spectroscopy analysis has been used to address the p-type formation mechanism. It depicts that (As-Zn-2V(Zn)) and [(AS(Zn)-2V(Zn))+N-O] complexes are responsible for p-conduction in codoped and tridoped ZnO films, respectively. The fabricated p-n homojunctions (n-ZnO:Al/p-ZnO:Al-As and n-ZnO:Al/p-ZnO:Al-As-N) clearly showed the typical rectification characteristics.