High quality, high density, and well-aligned zinc oxide (ZnO) nanorods have been synthesized on cost-effective printed circuit board (PCB) substrates via a simple, seedless, onestep, low-temperature hydrothermal method based galvanic cell structure. It was found that the outer diameters of the ZnO nanorods range from 50 nm to 400 nm. | VNU Journal of Science: Mathematics – Physics, Vol. 33, No. 2 (2017) 29-33 A Simple, One-step, Seedless Hydrothermal Growth of ZnO Nanorods on Printed Circuit Board Substrate Mai Hong Hanh*, Nguyen Viet Tuyen, Pham Van Thanh, Hoang Chi Hieu Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Hanoi, Vietnam Received 20 March 2017 Revised 25 April 2017; Accepted 25 May 2017 Abstract: High quality, high density, and well-aligned zinc oxide (ZnO) nanorods have been synthesized on cost-effective printed circuit board (PCB) substrates via a simple, seedless, onestep, low-temperature hydrothermal method based galvanic cell structure. It was found that the outer diameters of the ZnO nanorods range from 50 nm to 400 nm. The as-grown ZnO nanorods prefer to grow along the c axis. The morphologies of the ZnO nanorods were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The crystallinity properties were characterized by Raman spectroscopy and photoluminescence (PL) spectroscopy. Keywords: ZnO nanorods, printed circuit boards (PCB), hydrothermal method. 1. Introduction ZnO, a direct wide band gap ( eV) semiconductor with a large exciton binding energy (60 meV) is considered to be one of the most important semiconductor materials due to its excellent electrical and optical properties and wide applications in ultraviolet lasers, photodetectors, solar cells, chemical and bio sensors [1-6]. For these applications, it is essential to have one-dimensional (1D) ZnO nanocrystals such as nanorods, nanowires, nanotubes with good alignment, high crystallinity, and high density. Recently, well-aligned ZnO nanorods have been successfully grown on different kinds of substrates by using a simple, low-temperature, hydrothermal technique [7-8]. To produce wellaligned ZnO nanorods, researchers have used both expensive substrates, such as GaN, Si, or sapphire, and low-cost substrates, such as ITO or FTO, which usually require the additional .
