Controllable growth of ZnO nanorod arrays with different densities and their photoelectric properties

Shujie Wang,Shuxi Dai,Ke Cheng,Yayan Zhang,Zuliang Du,Chongshun Song

doi:10.1186/1556-276x-7-246

Abstract

Since the photoelectric response and charge carriers transport can be influenced greatly by the density and spacing of the ZnO nanorod arrays, controlling of these geometric parameters precisely is highly desirable but rather challenging in practice. Here, we fabricated patterned ZnO nanorod arrays with different densities and spacing distances on silicon (Si) substrate by electron beam lithography (EBL) method combined with the subsequent hydrothermal reaction process. By using the EBL method, patterned ZnO seed layers with different areas and spacing distances were obtained firstly. ZnO nanorod arrays with different densities and various morphologies were obtained by the subsequent hydrothermal growth process. The combination of EBL and hydrothermal growth process was very attractive and could make us control the geometric parameters of ZnO nanorod arrays expediently. Finally, the vertical transport properties of the patterned ZnO nanorod arrays were investigated through the microprobe station equipment, and the I-V measurement results indicated that the back-to-back Schottky contacts with different barrier heights were formed in dark conditions. Under UV light illumination, the patterned ZnO nanorod arrays showed a high UV light sensitivity, and the response ratio was about 104. The controllable fabrication of patterned ZnO nanorod arrays and understanding their photoelectric transport properties were helpful to improve the performance of nanodevices based on them.

Highlights

There is a growing interest in designing new architectures for enhancing the performance of photoelectric devices [1]
Photoelectric devices based on ZnO, CdS, ZnS, InP, SnO2, and Si nanowires or nanorod arrays offer the advantages of enhanced light absorption, improved carrier collection efficiency, and longer lifetime for minority carriers compared to conventional planar photoelectric devices, which can find many applications from field emission devices, sensors, solar cells, nanogenerators to UV photodetectors with the significantly improved performances [3,4,5,6,7,8,9]
Various synthetic methods have been developed for the growth and fabrication of vertically aligned ZnO nanorod arrays, which can be classified into two categories: vapor-phase and hydrothermal synthesis

Summary

Introduction

There is a growing interest in designing new architectures for enhancing the performance of photoelectric devices [1]. Various synthetic methods have been developed for the growth and fabrication of vertically aligned ZnO nanorod arrays, which can be classified into two categories: vapor-phase and hydrothermal synthesis. The hydrothermal synthesis method is more favorable for the practical applications due to its low growth temperature, low cost, and good potential for scale-up. This method avoids the usage of gold catalyst, which is commonly used in vapor-phase methods and may introduce the residual catalyst atoms into the ZnO rod arrays [11,12,13]. The development of nanofabrication techniques and equipments such as electron beam lithography (EBL), nanoimprint lithography, laser interference lithography, and nanosphere lithography provide us the potential opportunity to fulfill this goal [18]

Methods

Results

Conclusion