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 $24.6cm2/Vs$⁠.