Fabrication and characterization of well-aligned, high density ZnO nanowire arrays and their realizations in Schottky device applications using a two-step approach

Abstract

We report a two-step general and viable approach for preparing a large area of high density and horizontally well-aligned arrays of zinc oxide nanowires (ZnO NWs) for the realization of Schottky device applications on inexpensive, flexible polymer substrate. A modified chemical vapor deposition (CVD) process is initially used for synthesizing the highly efficient and rapid growth of vertical ZnO NW arrays along their [0001] direction, which is perpendicular to the donor substrate surface without using any metal catalyze. This is followed by transferring the NWs to a receiver substrate by a dry contact printing method. Utilizing the ZnO NWs synthesized by our method, a fully controllable and relatively large separation between the adjacent rows of silver (Ag) electrodes for the electrical contact with the NWs can be obtained using a photolithographic process. The printed ZnO NWs are well aligned along their c-axis, resulting in a spontaneous polarization which leads to a potential gradient along the length of the individual NW. This coupled with the effect of the surface states in the ZnO NWs result in the formation of a Schottky contact at the Ag/ZnO NW interface. Hence, virtually all of the ZnO NW arrays are functional as Schottky diodes which display non-linear current–voltage characteristics with good rectifying diode-like behaviour.