Modeling and characterization of Zinc Oxide thin film transistors

Abstract

Recently, oxide TFTs have been investigated as current-driving devices for the future display. Due to the high mobility, transparency, and low-temperature processing, they have attracted much attention all over the world. In this thesis, the electrical characteristics of the ZnO TFTs is measured, analyzed, and modeled. In fact, the output characteristic and the transfer curve do not supply a variety of information. On the contrary, C-V data can give the important information such as the flat-band voltage, induced charge density, and etc. Thus, as the first step, the quasi-static C-V (QSCV) measurement is performed to get the reliable C-V data. The unique features, which are not shown in the general MOSFETs, are observed. The origin of this phenomenon is interpreted in detail. With the measured C-V data, several electrical values are obtained, and the device characteristics are analyzed based on them. Especially, modeling the electrical characteristics is intricate, owing to the trap densities which are included in the ZnO film. Therefore, the extraction of the accurate trap distribution in the ZnO film is critical. In order to detect the trap densities, we will apply the C-V method to the ZnO TFTs. Finally, the extracted trap densities will be verified through the simulation using Silvaco ATLAS.