OPTIMAL PROCESS FOR THE HIGH PERFORMANCE OF ZnO THIN FILM TRANSISTORS

摘要

The object of this study was to improve the performance of ZnO thin film transistors (TFTs) by the optimal process such as a controlling of oxygen partial pressure, rapid thermal annealing (RTA) process, and proton irradiation. ZnO thin films are deposited as channel layer with various oxygen partial pressures. After ZnO-TFTs fabrication, in order to improve the interface characteristics between source/drain electrodes and the channel layer, we have conducted the RTA process. However, the conductivity of the ZnO channel layer was dramatically increased during the RTA process. Therefore, the RTA-treated ZnO-TFTs did not show the proper output and transfer characteristics. In order to control the electrical properties of the channel layer, we exposed the RTA-treated ZnO-TFTs to 6.1-MeV proton irradiation beam energy at fluences from 6.7× 10~(12) cm~(-2) to 6.5× 10~(14) cm~(-2). The conductivity of the ZnO thin film decreased after high-dose proton irradiation. The field effective mobility of ZnO-TFTs increased from 1.65 cm~2/V-s to 4.12 cm~2/V-s after the RTA and the high dose proton irradiation. We obtained an enhancement of ZnO-TFT performance using the controlling of oxygen partial pressure, RTA process, and high-dose proton irradiation.