Revealing Dielectric's Degradation Effect on Charge Transport in Dual Gate In–Ga–Zn–O Thin Film Transistor via Accumulation–Depletion Operation Mode

An accumulation–depletion (AD) mode for IGZO‐TFT to reveal dielectric layers degradation effect on charge transport is proposed, realizing a modulation of the vertical spatial location of accumulated carriers at keeping a constant sheet concentration, which enables to investigate the relationship between carriers’ location and their transport behaviors. The drastic change of carriers’ mobility under different AD modes is observed. Based on the temperature dependence analysis and technology computer‐aided design simulation, it is found that when compressing the accumulated carriers closer to the Al 2 O 3 dielectric layer (from average position 1.75 to 0.75 nm) by the depletion bias, the mobility decreases more than threefolds due to the higher disorder from dielectric layer. The AD mode provides a more quantitative pathway for revealing how intensely the dielectric layer can degrade the charge transport and might be developed as a method for evaluating the quality of the semiconductor–dielectric interface.