Synthesis of ZnO nanowires using lower temperature vapor based methods

In this paper, we elaborate on protocols for growing ZnO nanowires using different vapor deposition techniques to provide a comparative study for low temperature based deposition. Effects of various parameters ranging from process temperatures to material compositions were investigated. Growth from ZnO thin film seed layers and catalytic growth using Au nanoparticles were performed as well as growth on blank Si substrates for comparison. Detailed results of SEM and XRD studies are presented for the ZnO nanowires. The lowest temperature achieved was approximately 750 °C with nanowires having diameters of 30-50 nm and lengths of 200-300 nm using VS method with a ZnO thin film seed to obtain complete surface coverage. In order to make the vapor based methods compatible with biosensors with monolithic readout circuits, the conventional thermal budget of commonly employed CMOS technology (usually around 450 °C) needs to be considered. Thus, lower temperature growth is preferable. In this regard, we address the temperature aspect of the growth for CMOS compatibility. We identify the effects of important process parameters and present a comprehensive investigation and comparative study of various factors on ZnO nanowire growth.