Enhanced electrical properties of dual-layer channel ZnO thin film transistors prepared by atomic layer deposition

The thin film transistors (TFTs) with a dual-layer channel structure combing ZnO thin layer grown at 200 degrees C and ZnO film grown at 120 degrees C by atomic layer deposition are fabricated. The dual-layer channel TFT exhibits a low leakage current of 2.8 x 10(-13) A, I-on/I-off ratio of 3.4 x 10(9), saturation mobility mu(sat) of 12 cm(2) V-1 s(-1), subthreshold swing (SS) of 0.25 V/decade. The SS value decreases to 0.18 V/decade after the annealing treatment in O-2 due to the reduction of the trap states at the channel/dielectric interface and in the bulk channel layer. The enhanced performance obtained from the dual- layer channel TFTs is due to the ability of maintaining high mobility and suppressing the increase in the off-current at the same time. (C) 2017 Elsevier B.V. All rights reserved.