(A) study on indium oxide thin-film transistors with high current through buffer layer engineering and trench structure

Abstract

High mobility and high current driving characteristics are essential to realize ultra-high resolution and ultra-realistic displays. In this study, high mobility characteristics were realized through a trench-structured oxide thin film transistor in which different materials were applied to the bottom and side buffer layers. In previous trench- structured thin film transistors, since the sputtering method had been used to obtain high current driving characteristics, the uniformity of the thin film has deteriorated. However, in this study, the effect of increasing the driving current can be obtained even when the active layer is deposited through the atomic layer deposition method. When the Al2O3 buffer layer was applied to the planar structure transistor, the resistance of the active layer was very low and exhibited conductive characteristics. When the SiO2 buffer layer was applied, stable switching characteristics were exhibited, but relatively low driving current was obtained. It was analyzed that the effect of increasing the driving current appeared because oxygen vacancies and hydrogen, which are shallow donors, diffused from the Al2O3 buffer layer to the active layer. In a single oxide TFT, the active layer in contact with Al2O3 has a high carrier concentration to increase current and mobility, and the part in contact with SiO2 has a relatively low carrier concentration and high thin film roughness to keep the turn-on voltage not moving significantly to the negative direction. The validity of this study was proved by various quantitative and qualitative analyses for oxygen vacancies and hydrogen, and investigating the device characteristics by adjusting the bottom channel layer.