Ge-doped ZnO nanowire arrays as cold field Emitters with excellent performance.

Abstract

Elemental doping is an efficient strategy to modify the electronic and optoelectronic properties of semiconductor materials. In this work, a high-quality Ge-doped tapered ZnO nanowire array was prepared via a simple chemical vapor deposition approach. The I-V and light emission behaviors were investigated based on a single nanowire with good electrical conductivity. The kelvin probe force microscopy (KPFM) and ultraviolet photoelectron spectroscopy (UPS) characterizations indicate that the doped nanowires possess a largely reduced work function relative to that of the pure ZnO nanostructures. These advantages allow Ge-doped ZnO nanowire arrays to deliver excellent field emission performance, including low turn-on and threshold fields, high emission current and long-term stability.