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

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 (mu (FE)) higher than LTPS (100 cm(2)/(V center dot s)). Here, we design ZnAlSnO (ZATO) homojunction structure TFTs to obtain mu (FE) = 113.8 cm(2)/(V center dot s). The device demonstrates optimized comprehensive electrical properties with an off-current of about 1.5 x 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.

Automated summary

AOS have unique advantages in transparent and flexible TFTs, but obtaining higher mu (FE) than LTPS has been difficult. In this study, ZnAlSnO homojunction TFTs were designed to achieve mu (FE) = 113.8 cm(2)/(V center dot s). The device exhibited optimized electrical properties with low off-current, threshold voltage, and subthreshold swing. The homojunction active layer, with a combination of micro-crystallization and carrier suppressor concentration gradient distribution, allowed for reduced off-current and positive shift in threshold voltage while maintaining high field-effect mobility. This research points to a promising direction for high-performance AOS TFTs.