Overview

ZnO is attracting intensive attention for its versatile applications in transparent electronics, UV emitter, piezoelectric devices, chemical sensor and spin electronics. As one of the direct wide band gap semiconductors, it has advantages over GaN due to its larger exciton binding energy, better lattice match on heteroepitaxial growth and availability of single crystal substrate. Large effort has been invested in the growth of nanostructured ZnO to explore its potentials for nanoscale device applications. ZnO nanobelts, nanowires, nanorings, and nanohelixes demonstrate the diversity of ZnO nanostructures family. This review presents recent research on ZnO nanostructures. Issues of synthesis methods, optical, electrical, gas sensing and magnetic properties are summarized. These progresses constitute the basis for developing future applications in nanoscale electronics, optoelectronics, chemical sensor and spintronics.

Keywords: wide band gap semiconductor; nanostructures; transparent electronics; UV emission; chemical sensor; spintronics

1. Introduction

Zinc oxide (ZnO) is one of the most important functional oxide semiconductors because of its unique properties and potential applications in manifold fields, such as transparent electronics, ultraviolet (UV) light emitter, surface acoustic wave (SAW) devices and spin electronics. Invisible thin film transistors (TFTs) using ZnO as an active channel achieve much higher field effect mobility (7 cm ²/V s) than amorphous silicon TFTs (0.5 cm ²/V s) [1 3]. ZnO has been proposed to be a more promising UV emitting phosphor...