Numerical investigation of organic thin-film transistors using a thermionic field emission model

Charge injection barriers at the electrode/semiconductor interface were considered for numerical investigation of electrical characteristics in realistic organic thin-film transistors (OTFTs). A new thermionic field emission (TFE) model, which addresses tunneling of thermally excited electrons, was used as the carrier injection model of OTFTs in this study. Device simulation for an n-channel OTFT with a bottom-gate, bottomcontact configuration was performed with a thin-film organic transistor advanced simulator (TOTAS). Typical electrical characteristics of realistic OTFTs such as severe nonlinearity in output characteristics were reproduced by this simulation using the TFE model. The effects of contact-arealimited doping for n-channel OTFTs were also examined from the simulation results, suggesting that highly doped semiconducting layers prepared over contact electrodes can neutralize the effect of a Schottky energy barrier. Both the simulation technique with the TFE model and the contactarea-limited doping are promising in designing and developing high-performance OTFTs.