Wang et al. Nanoscale Research Letters 2012, 7:246 http://www.nanoscalereslett.com/content/7/1/246 N A N O E X P R E S S Open Access Controllable growth of ZnO nanorod arrays with different densities and their photoelectric properties Shujie Wang, Chongshun Song, Ke Cheng, Shuxi Dai, Yayan Zhang and Zuliang Du* 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. Keywords: ZnO nanorod arrays, EBL, Hydrothermal, Photoelectric Background There is a growing interest in designing new architec- tures for enhancing the performance of photoelectric devices [1]. Due to the uniquely combined optical and electrical characteristics, ordered nanorod arrays have received considerable attentions for this goal [2]. Photo- electric 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 com- pared 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 perfor- mances [3-9]. Among them, ZnO nanorod array is one of the most promising materials for photoelectric * Correspondence: zld@henu.edu.cn Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004, People’s Republic of China devices due to its large exciton binding energy (60 meV), versatile synthesis, high mechanical and thermal stabili- ties, and nontoxic n-type nature [10]. Recently, various synthetic methods have been devel- oped for the growth and fabrication of vertically aligned ZnO nanorod arrays, which can be classified into two cat- egories: 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. More import- antly, this method avoids the usage of gold catalyst, which is commonly used in vapor-phase methods and may intro- duce the residual catalyst atoms into the ZnO rod arrays [11-13]. Based on the hydrothermal method, three dimen- sional (3D) ZnO hybrid architectures and “nanoforest” hierarchical ZnO arrays have been synthesized [14,15]. Theoretical and experimental works also have been car- ried out on the ZnO nanorod arrays based photoelectric devices and shown that the photoelectric response and © 2012 Wang et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.