A semiphysical current-voltage model with a contact ideality factor for disordered thin-film transistors

A semiphysical current-voltage model for disordered thin-film transistors is presented. In the proposed model, a power-law function is employed to describe the drift current in the above-threshold region while a Fermi-Dirac function-like exponential formula is introduced to describe the diffusion current in the subthreshold region. In particular, this subthreshold current model is more physically meaningful compared with the typical exponential model. In addition, it also contains an ideality factor for the source and drain contacts, explaining the vertical separation of the drain current for different drain voltages in the subthreshold region. Using the proposed approach, analytical expressions are derived, providing good agreement with experimental results in both the linear and saturation regimes.