Improving Charge Trapping/Detrapping Characteristics of Amorphous In-Ga-ZnO Thin-Film-Transistors Using Microwave Irradiation.

Abstract

We investigated the effect of post-deposition annealing (PDA) on the gate-bias-stress-induced charge trapping/detrapping phenomenon in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). To evaluate device reliability, we used the microwave irradiation (MWI), rapid thermal annealing (RTA), and conventional thermal annealing (CTA) methods for PDA of the TFTs and compared the resulting device performances. Fabricated devices were measured in the dark and under light illumination under positive and negative gate-bias-temperature stress (PBTS and NBTS, respectively). Because microwave energy was transferred directly to the substrate in a short time of 2 min in the MWI device, defects were removed more effectively. The obtained results indicated that the threshold voltage (Vth) shift of the MWI-treated a-IGZO TFT with different temperatures and gate bias stresses in the dark and under light illumination was the smallest and the most reliable. Further, comparisons of the Vth recovery characteristics in the dark and under light illumination indicated that charge detrapping behaviors were enhanced under the latter condition. Furthermore, the average effective energy barrier based on Arrhenius plots was extracted. Therefore, the MWI method is considered promising for fabricating next-generation displays on various substrates.