Electrochemical Route to p-Type Doping of ZnO Nanowires

p-Type ZnO nanowires doped with Ag were successfully obtained by low-temperature electrochemical growth followed by annealing. The p-type conductivity is achievable only under certain growth conditions such that the incorporation of Ag does not significantly affect the quality of the ZnO nanowires. The applied potential during growth plays a key role in achieving p-type conductivity. As the potential decreases below a critical value of -0.65 V (more negative relative to Ag/AgCl), the conductivity changes from n- to p-type in the doped ZnO nanowires. In addition, p-type ZnO nanowires exhibit a band gap reduction and strong acceptor-related photoluminescence, while n-type nanowires show band gap broadening with a strong donor-bound exciton emission. This study sheds light on the rational growth of p-type ZnO nanomaterials by low-cost electrochemical deposition.