Performance enhancement of carbon nanotube thin film transistor by yttrium oxide cappingElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nr08676h

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 (Y 2 O 3 ) capping is helpful in improving both I ON and μ of CNT-TFTs. Combining Y 2 O 3 capping and Al 2 O 3 passivation, unipolar CNT-TFTs with high I ON / I OFF (>10 7 ) 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. Y 2 O 3 capping can improve the I ON and mobility of carbon nanotube thin film transistors while suppressing its ambipolarity.