Effect of Metal Capping on the Stability of Amorphous Si–Zn–Sn–O Thin Film Transistor by Suppressing Ambient Effect

Abstract

By adopting metal capping layer (MC layer), electrical properties, such as field effect mobility, on current, and subthreshold swing showed enhanced characteristics with 24.996 cm2/Vs, 2.1×10−4 and 0.34 V/decade, respectively. In addition, the stability of the negative bias thermal stress (NBTS) against the ambient environment has been shown to be enhanced by the MC layer which acts like passivation layer. Without additional passivation layer, MC layer alone sufficiently inhibited the ambient effect to show low threshold voltage shift of 0.21 V compared with 0.89 V of conventional TFT. MC layer structure, enhancing the electrical characteristic and stability, had the advantages of a process that was much simpler than conventional process for high performance and stability.