Effect of an Electrical Field Applied to the Metal Capping Layer on the Electrical Properties of SiZnSnO Thin-Film Transistors for Touch Sensor Application

Thin-film transistors (TFTs) have been studied for their high mobility and stability to facilitate the development of TFT-based touch sensors and electronic devices. A metal capping (MC) layer on the back channel of Si–Zn–Sn–O(SZTO) TFTs has been proposed to improve the electrical properties. MC, when adopted on the channel layer, has low resistance, leading to an improvement in the mobility of the TFT. The mobility of Ti/Al MC TFT has improved from 20.7 to 37.9 cm² V⁻¹ s compared to the pristine TFTs. Applying a potential voltage to the MC layer sensitively modulates the I–V characteristics of the TFT. The present study applies a voltage of 60 mV, similar to that of the human body, to MC-TFTs to explore their possibilities as human touch sensors. The sensitivity and the energy bandgap modulation are also discussed.