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

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 8x10(-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 1x10(19) to 1x10(20) cm(-3) due to oxygen adsorption. (C) 2007 American Institute of Physics.