Influence of Channel Stoichiometry on Zinc Indium Oxide Thin-Film Transistor Performance

Thin-film transistors using a semiconductor of the form (ZnO)x( In2O3)1- x were fabricated via combinatorial RF sputtering. Stoichiometries varied from x=0.5 to x=1. Two sets of devices were annealed under oxygen at 300degC and 600degC, with another left as deposited. Devices fabricated with a zinc oxide fraction of 0.67plusmn0.02 were found to exhibit the highest mobilities of 35 cm2/Vmiddots for 300degC annealing conditions. Peak performance was found for x=0.75plusmn0.02, which yielded near-zero turn-on voltages, inverse subthreshold slopes of 0.3 V/dec, and on/off ratios up to 109.