Effect of Tunable Sub-Source and Sub-Drain Device Behavior in Four-Terminal Operation Using Metal-Capping Thin-Film Transistors

Abstract

We report on a metal-capping (MC) structure with threshold voltage (V-th) tunability via four-terminal driving. Amorphous oxide semiconductors (AOSs) are emerging as promising next-generation semiconductor materials due to their remarkable properties, such as high field-effect mobility, uniformity, and excellent transmittance in the visible light region. The MC structure is a simple structure that can improve the characteristics of a thin-film transistor (TFTs) based on AOSs. By applying additional voltage to this MC layer, we were able to control the amount and direction of carrier flow during the I-V operation. With the four-terminal drive, the V-th of the MC TFT can be modulated according to the voltage applied to the MC layer. When a negative voltage is applied to the MC layer, the V-th shifts to the negative region, and when a positive voltage is applied, the V-th shifts to the positive region. With the four-terminal MC TFT, we expect to be able to compensate for V-th modulated by external stresses that significantly affect the display pixels. Furthermore, it is expected that this operating principle can be utilized in many application systems, such as sensors.