Electrical Performance Enhancement of Al–Zn-Sn–O Thin Film Transistor by Supercritical Fluid Treatment

In this letter, a low-temperature supercritical fluid (SCF) treatment was employed to enhance the electrical and optical properties of amorphous Al-Zn-Sn-O thin film transistors (a-AZTO TFTs) for flat-panel displays. The carrier mobility and threshold voltage of a-AZTO TFT were improved significantly after SCF process because of the reduction of trap density in the a-AZTO active layer. In addition, the SCF-treated a-AZTO TFT exhibited superior electrical reliability and less degradation after negative gate bias illumination stress. X-ray photoelectron spectroscopy analysis confirmed that the proposed SCF treatment could effectively oxidize a-AZTO film and change the oxidation states of Sn, resulting in the improvement of a-AZTO TFT device characteristics.