Reduction of contact resistance between organic semiconductor and electrodes with thiol-based self-assembled monolayer in low-density and lying-down phase

Abstract

We report on a treatment of a thiol-based self-assembled monolayer with long alkyl chains on source/drain electrodes of organic thin-film transistors with a bottom-contact configuration. The performance of organic thin-film transistors such as field effect mobility and on/off ratio is improved by performing this treatment in the early stage. However, excessive treatment conversely reduces the field-effect mobility with a threshold voltage shift. We have found these results due to the difference in the density and the orientation of the thiol molecules. Thiol molecules adsorbed on source/drain electrodes in the lying-down phase cause a significant effect to reduce the contact resistance between the electrodes and a semiconductor depending on the energy barrier height at the interface. © 2008 The Japan Society of Applied Physics.