Amorphous gallium indium zinc oxide thin film transistors: Sensitive to oxygen molecules

Abstract
In this study, the authors report characteristic of indium gallium zinc oxides (GIZOs) which is strongly associated with the film surface. In ambient air, turn-on voltage of GIZO thin film transistors is approximately − 7 V . However, at the pressure of 8 × 10 − 6 Torr , the turn-on voltage dramatically shifts to nearly − 47 V of the negative gate bias direction. When the oxygen is introduced in the chamber, the turn-on voltage returns to the normal value, that of air. It is believed that the adsorbed oxygen forms depletion layer below the surface, resulting in V on shifts. The carrier concentration of the channel varies from 1 × 10 19 to 1 × 10 20 cm − 3 due to oxygen adsorption.