Lambert W-function based modelling of P-OTFTs and application to low temperature measurements

摘要

In this paper, a physically-based model was adapted to P-type organic thin-film transistors (P-OTFTs) by describing the accumulation charge with a Lambert W (LW) function in order to extract their figures of merit as threshold voltage, low-field mobility and subthreshold slope related to the interface traps density. This continuous and differentiable model, implemented for the first time on OTFTs, allows an accurate evaluation of the output and transfer characteristics, reproducing well the OTFT behaviour below and above the threshold region. Additionally, it was validated for different channel lengths (from 10 to 100 mu m), taking into account short-channel effects. This model was also used to extract the parameters of P-OTFTs measured at low temperatures, showing a thermally activated transport in the polymer organic semiconductor (OSC) with an effective width of localized states around 90 meV and a relatively high band-like mobility. We also showed that the evolution of the threshold voltage versus temperature was related to the electrostatic effect of the interface trapped charge. The comparison between classical extraction methods and our LW-function based method validated the application of our model to P-OTFTs parameters extraction, opening a possibility for compact modelling.