Improvement of subthreshold current transport by contact interface modification in p-type organic field-effect transistors

The charge injection efficiency of organic field-effect transistors (OFETs) is found to be a critical factor determining the subthreshold characteristics of these devices. OFETs fabricated using a wide band gap organic semiconductor and gold source/drain contacts display large threshold voltage and poor subthreshold characteristics. Insertion of a metal-oxide charge injection layer at the contact/semiconductor interface lower the injection barrier height, resulting in marked improvements in threshold voltage and subthreshold slope and strong suppression of the short-channel effect. The improved subthreshold characteristics are attributed to enhanced charge injection and the consequent promotion of charge accumulation.