Extracting Device Parameters of TFTs With Ultrathin Channels at Low Temperatures by Particle Swarm Optimization

Thin-film transistors with ultrathin channels are fabricated and characterized at low temperatures down to 100 K in this study. Relying on a diffusive charge model, interfacial localized-state density and apparent carrier mobility are extracted from the measured data. The extraction is carried out by a numerical procedure based on particle swarm optimization (PSO). All the extracted parameters vary clearly with lowering temperatures (300
$\sim$
100 K), which are explained by phonon suppression, thermally-strained chemical bonds and carrier transport with effective mobility involving hopping mechanisms. This work demonstrates parameter extraction by PSO for the first time and highlights the challenges of non-crystalline transistors working at low temperatures.