A normally off high-voltage InGaZnO transistor with drain offset region modulated by an InZnO layer

Abstract

This work presents a normally off high-voltage indium-gallium-zinc-oxide (IGZO) thin-film transistor (TFT) featuring a drain offset region modulated by the IZO layer (IMO, IMO-IGZO TFT). In addition to decreasing the specific on-resistance (Ron,sp) by more than three orders of magnitude, the IMO structure further elevates the breakdown voltage by optimizing the thickness of the IZO layer (tIZO) compared to the Offset TFT. Through TCAD simulation, the underlying mechanism responsible for the improved performance of the IMO-IGZO TFT is elucidated. The introduced IZO modulating layer effectively increases carrier concentration and rebuilds the electric field within the offset region. Consequently, the IMO-IGZO TFT with a 6 nm thick IZO modulating layer and 3.5 μm length offset region attains a breakdown voltage of 410 V and demonstrates favorable Ron,sp of 5.3 × 103 mΩ × cm2. This results in a Baliga's figure of merit of 31.72 kW/cm2, surpassing conventional and Offset TFTs by factors of 186 and 3048, respectively.