The Electrical Properties of Asymmetric Schottky Contact Thin-Film Transistors with Amorphous-In2Ga2ZnO7

Abstract

Asymmetric Schottky contact thin-film-transistors (ASC-TFTs) with an amorphous-In2Ga2ZnO7 channel were fabricated, and their operation characteristics were examined. Ti, Ni, and Pt were evaluated as source/drain metal, and the variations in the device performance were analyzed in terms of energy level and bias polarity, which were carefully simulated to understand the influence of the contact properties on the device performance. The contact nature largely influenced the distribution of potential under the given gate and drain biases, as well as the accompanying carrier accumulation layer and current path formation. Schottky-type contact induced conduction path formation even on the back surface of the channel when drain voltage was high even with sufficiently high gate bias being applied. Based on these results, by applying different metal for each source and drain metal, ASC-TFTs integrating TFTs and Schottky diodes were fabricated, which showed a rectification ratio of drain current higher than 10(8) according to the bias direction. In addition, the transfer and output characteristics of ASC-TFTs were evaluated for various operation regimes, and the roles of the Schottky junction in device operation were studied in detail.