Performance enhancement of carbon nanotube thin film transistor by yttrium oxide capping.

Carbon nanotube thin film transistors (CNT-TFTs) are regarded as promising technology for active matrix pixel driving circuits of future flat panel displays (FPD). For FPD application, unipolar thin film transistors (TFTs) with high mobility (μ), high on-state current (I), low off-current (I) at high source/drain bias and small hysteresis are required simultaneously. Though excellent values of those performance metrics have been realized individually in different reports, the overall performance of previously reported CNT-TFTs has not met the above requirements. In this paper, we found that yttrium oxide (YO) capping is helpful in improving both I and μ of CNT-TFTs. Combining YO capping and AlO passivation, unipolar CNT-TFTs with high I/I (>10) and low I (∼pA) at -10.1 V source/drain bias, and relatively small hysteresis in the range of -30 V to +30 V gate voltage were achieved, which are capable of active matrix display driving.