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

Abstract

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_ON), low off-current (I_OFF) 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 (Y₂O₃) capping is helpful in improving both I_ON and μ of CNT-TFTs. Combining Y₂O₃ capping and Al₂O₃ passivation, unipolar CNT-TFTs with high I_ON/I_OFF (>10⁷) and low I_OFF (∼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.