Achieving High Mobility in IGTO Thin-Film Transistors at a Low Temperature via Film Densification

The effects of chamber pressure ( {P}_{\text {C}} ) on the structural and chemical properties of an indium gallium tin oxide (IGTO) channel layer were examined. Smoother and denser IGTO films were obtained with decreasing {P}_{\text {C}} , which were explained based on the enhanced kinetic energy of sputtered particles due to fewer collisions with the plasma atmosphere. The resulting IGTO thin-film transistor exhibited a high mobility of 35.0 cm 2 /Vs, subthreshold gate swing of 0.17 V/decade, threshold voltage ( {V}_{\text {TH}} ) of −0.45 V, and {I}_{\mathrm {\scriptscriptstyle {ON/OFF}}} ratio >10 8 , even at a low annealing temperature of 150 °C.