A Comprehensive Physics-Based Compact Model for CNT Thin Film Transistors—Part II: Ohmic Contact

Abstract

In continuation to the preceding article, this part presents a study of electrical transport in Ohmic contact carbon nanotube thin film transistors (CNT TFTs). Here, the transistor model is implemented as a special case of the previously presented generalized model. Based on comparisons between simulated and experimental data, it is observed that optical phonon scattering in Ohmic contact CNT TFTs is fairly independent of gate and drain biases as opposed to the Schottky contact counterparts. Moreover, it is observed that transport is significantly affected by the channel length and alignment between CNTs as optical phonon scattering is found to be more pronounced for smaller channel lengths and greater alignments. The success of the model is supported by good agreement between simulations and a wide range of experimental data. This is verified by calculating the relative root mean square error (RMSE) which shows an average deviation in the order of ~15%. In comparison to previous CNT TFT models, this work introduces a generalized model, considering both Schottky and Ohmic contact-induced ambipolar and unipolar modes of transport, closely following the essential transport physics.