The generation of nanostructures on ZnO/Si surface

• Main Author: Xie, Jian.
• Other Authors: School of Materials Science and Engineering
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/51841
• Institution: Nanyang Technological University

Nanoscale one-dimensional (1D) semiconductor structures such as rods, tubes and wires have attracted much attention recently. ZnO nanorods are important because of their unique 1D structure with a direct wide band gap of 3.37eV and a large exciton binding energy of 60 meV at room temperature. These unique properties make it a promising material for applications in electronics, solar cells and other nanoscale optoelectronic devices. The purpose of this Final Year Project is to generate nanostructures on the surface of pre-coated silicon substrate. Precursor solution was prepared by mixing of Zinc Nitrate Hexahydrate and Hexamethylenetetramine in deionized (DI) water. Many factors like precursor solution concentration, reaction time and reaction temperature which have impact on the generation process of the nanostructures were introduced. The effect of these factors was discussed in the report in order to study the microstructure and optical properties of ZnO nanostructures. By using low temperature hydrothermal method, ZnO nanorods have been successfully generated under different conditions. Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Photoluminescence (PL) spectroscopy were used to characterize the microstructure features, crystal structures and chemical compositions of the ZnO nanostructures. The results show the diameter and length of the ZnO nanorods increase upon increasing the precursor concentration, reaction time and reaction temperature. It was found that the preferred orientation growth of the wurtzite structure of ZnO nanorods was along [0001] direction. The optical property of the ZnO nanorods was also studied by PL analysis. The measurement from the current-voltage (I-V) curve indicates the ideal diode characteristic performed by each ZnO/GaN nano-heterojunction. The success in the fabrication of a great number of fully ordered individual p-n nanojuctions are expected to provide the potential application for high density and efficient nano-devices, such as photovoltaic devices.