Device characteristics of amorphous In-Ga-Zn oxide thin-film transistors with varying channel thickness

Abstract

Channel thickness of thin-film transistors (TFTs) having amorphous In-Ga-Zn oxide channels has been optimized based on the device performance characteristics including output characteristics, transfer characteristics, and bias stress stability. The device performance initially improved as the channel thickness increased from 20 to 30 nm, but subsequently deteriorated with further increasing thickness to 40 nm. The 30-nm-channel TFT exhibited threshold voltage close to 0 V, the highest field-effect mobility (µFE), highest on/off ratio, and smallest threshold voltage shift under bias stress. The observed channel-thickness-dependent changes in device characteristics are attributed to the collective contribution of interface traps, fixed oxide charges, and mobile charges.