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

Abstract

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 (V-th) 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, V-th of -0.4 V, and high I-on/off ratio of >10(9) as well as a high field-effect mobility of 24.6 cm(2)/V s.