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

We present a transistor model to describe the field effect current/voltage (
${I}/{V}$
) relationship in single-wall carbon nanotube thin film transistors (CNT TFTs). Based on the nature of current transport, the model is subdivided to address Schottky contact and Ohmic contact CNT TFTs separately. In this part, the generalized theoretical model for the Schottky contact device is developed, and verified against experimental data. The primary aim of the model consists of determining the current across the CNT film, visualized as a network of interconnected CNTs. This is carried out by estimating the current across the individual CNTs and combining them using kirchhoff’s current law (KCL) while following current continuity conditions. The device electrostatics are defined following a capacitive model where the effects of interfacial states, traps, charges, and so on are addressed. The effects of phonon scattering on transport are also discussed. From experimental results, phonon scattering is found to be greater at low drain and high gate biases. This is directly explained in terms of the energy band diagram of the device under the influence of external bias. The inferences drawn from this study are expected to also be extendable to other Schottky field effect transistor (FET)-based devices.