High mobility thin film transistors with indium oxide/gallium oxide bi-layer structures

We investigate the transport properties of thin-film transistors using indium oxide (In2O3)/gallium oxide (Ga2O3) bi-layer stacks as the channel material. At low gate bias, we observe the transistor field-effect mobility increases with the film resistivity to mu(FE) = 51.3 cm(2)/Vs and ON/OFF current ratio to 10(8) due to combinatorial layer thickness modulation. With the Ga2O3 layer thickness ratio increase to R = 14.35%, these observations are accompanied with one-order-of-magnitude reduction in the transistor subthreshold swing to 0.38 V/decade and suggest a trap-limited conduction mechanism upon which the reduced scattering centers due to annihilation of subgap states improve the device electric characteristics without post-growth annealing. (C) 2012 American Institute of Physics. [doi:10.1063/1.3683518]