Atomic Layer Deposited Zinc Tin Oxide Channel for Amorphous Oxide Thin Film Transistors

Abstract

Bottom-gate thin film transistors with amorphous zinc tin oxide channels were grown by atomic layer deposition (ALD). The films maintained their amorphous character up to temperatures over 500 \(^{\circ}\)C. The highest field effect mobility was ~13 \(cm^2/V^.s\) with on-to-off ratios of drain current ~10\(^9\)-10\(^{10}\). The lowest subthreshold swing of 0.27 V/decade was observed with thermal oxide as a gate insulator. The channel layers grown at 170 \(^{\circ}\)C showed better transistor properties than those grown at 120 \(^{\circ}\)C. Channels with higher zinc to tin ratio (~3-4) also performed better than ones with lower ratios (~1-3).