High performance thin film transistor with cosputtered amorphous Zn–In–Sn–O channel: Combinatorial approach

Thin film transistors with a channel of Zn–In–Sn–O were fabricated via a combinatorial rf sputtering method. It was found that the role of the In atoms is to enhance the mobility and to shift the threshold voltage (Vth) negatively. On the other hand, the Sn fraction is critical for improving the overall trap density including the density-of-states of the bulk channel layer and the interfacial trap density at the ZnInSnO interface. The optimized transistor was obtained at a compositional ratio of Zn:In:Sn=40:20:40, which exhibited an excellent subthreshold gate swing of 0.12 V/decade, Vth of −0.4 V, and high Ion/off ratio of 109 as well as a high field-effect mobility of 24.6 cm2/V s.