P-type Sodium-doped Zinc Oxide Nanowire Arrays Grown by High-pressure Pulsed Laser Deposition

Abstract

Sodium-doped ZnO (ZnO:Na) nanowire arrays were grown with high-pressure pulsed laser deposition (HP-PLD). The influence of growth pressure and thickness of gold catalyst layer on the growth of ZnO:Na nanowires were systemically studied. It is found that c-orientated ZnO nanowire arrays grow on single crystal silicon substrates under the optimized condition, e.g. gold catalyst layer’s thickness of 4.2 nm, growth pressure of 3.33×10 Pa and growth temperature of 875 °C. X-ray diffraction pattern and X-ray photoelectron spectroscope analyses indicate that Na is introduced into ZnO nanowires successfully. Optical fingerprints of sodium-related acceptors in the low-temperature (15 K) photoluminescence spectrum are observed, such as neutral acceptor-bound exciton emission (3.356 eV, AX), free-electron to neutral-acceptor emission (3.312 eV, (e, A)), and donor-to-acceptor pair emission (3.233 eV, DAP). ZnO:Na nanowire arrays grown on ZnO:Al/sapphire substrates form the pn junction. The corresponding I-V curve measurements exhibit a clear rectifying behavior of pn homojunction, which further indicates that such ZnO:Na nanowire is of p-type conductivity. 156 无 机 材 料 学 报 第 29卷