Efficient charge injection from a high work function metal in high mobility n-type polymer field-effect transistors

We demonstrate efficient electron injection from a high work function metal in staggered transistors based on the high mobility poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}. Channel length scaling shows that the linear mobility for electrons remains higher than 0.1 cm(2)/V s when reducing the channel length to a few micrometers. Field-enhanced injection favors downscaling at a fixed lateral voltage and reduces the contact resistance to 11 k Omega cm at high gate voltages for channels of only a few micrometers. The contacts are asymmetric, with the source contribution dominating the overall resistance, consistent with an injection limited regime rather than bulk-limited as generally found in staggered transistors. (C) 2010 American Institute of Physics. [doi:10.1063/1.3424792]