2002/02/27 by Ghosh, Avik W., Zahid, Ferdows, Damle, Prashant S. +1
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.cond-mat/0202519
We investigate the origin of asymmetry in the measured current-voltage (I-V) characteristics of molecules with no inherent spatial asymmetry. We establish that such molecules can exhibit asymmetric I-V characteristics due to unequal coupling with the contacts. In contrast with spatially asymmetric molecules, conduction takes place through essentially the same level in both bias directions. The asymmetry arises from a subtle difference in the charging effects, which can only be captured in a self-consistent model for molecular conduction. For HOMO-based conduction, the current is smaller for positive voltage on the stronger contact, while for LUMO conduction, the sense of asymmetry is switched.