A STUDY OF ZINC OXIDE BASED SEMICONDUCTOR WITH GOLD NANOPARTICLES

Abstract

Zinc oxide (ZnO) is a very promising material for application of semiconductor devices, because it has a number of advantages including the high electron mobility, high thermal conductivity, wide and direct band gap, and large exciton binding energy. These aspects make ZnO suitable for a wide range of semiconductor devices such as transparent thin film transistors (TFTs), transparent conducting oxides (TCOs), light emitting diodes (LEDs) and photodectors. Furthermore, among noble metal, gold nanoparticles (Au NPs) exhibit unique optical, electronic, and magnetic properties not seen at the bulk scale, which makes them attractive for semiconductor devices applications. In this study, ZnO based semiconductors with Au NPs were investigated. Firstly, by introducing the Au NPs into the channel layer of amorphous indium gallium zinc oxide (a-IGZO) TFTs, it was shown that the position and size of Au NPs significantly influenced the threshold voltage and off-current. These results can be explained by assuming that Au NPs function not only as electron injection sites but also as electron trap sites, and form the carrier conduction path which leads to the current leakage in the a-IGZO channel layer. In addition, it was found that the carrier conduction path is particularly affected by the distance between the Au NPs. Secondly, the structural, electrical, and optical properties of Ga doped ZnO (GZO) multilayer structure have been investigated. The sheet resistance and resistivity of GZO/Au/GZO multilayers decrease with increasing the Au interlayer thickness. Moreover, the insertion of an Au interlayer between top and bottom GZO layers causes a reduction in the optical transmittances. However, the GZO/Au/GZO multilayer with a 9 nm thick Au interlayer exhibits relatively low resistivity and high peak transmittance for advanced optoelectronic devices.