Homojunction structure amorphous oxide thin film transistors with ultra-high mobility

Abstract Amorphous oxide semiconductors (AOS) have unique advantages in transparent and flexible thin film transistors (TFTs) applications, compared to low-temperature polycrystalline-Si (LTPS). However, intrinsic AOS TFTs are difficult to obtain field-effect mobility (μ FE) higher than LTPS (100 cm2/(V·s)). Here, we design ZnAlSnO (ZATO) homojunction structure TFTs to obtain μ FE = 113.8 cm2/(V·s). The device demonstrates optimized comprehensive electrical properties with an off-current of about 1.5 × 10–11 A, a threshold voltage of –1.71 V, and a subthreshold swing of 0.372 V/dec. There are two kinds of gradient coupled in the homojunction active layer, which are micro-crystallization and carrier suppressor concentration gradient distribution so that the device can reduce off-current and shift the threshold voltage positively while maintaining high field-effect mobility. Our research in the homojunction active layer points to a promising direction for obtaining excellent-performance AOS TFTs.