In this paper a new asymmetric Schottky barrier MOSFET structure is presented which employs a thin interfacial insulator layer in the metal/silicon junction at the source. This asymmetric structure leads to a considerable improvement in the on/off ratio of the device by significantly lowering the off-current while leaving the on-current of the transistor unaffected. In addition the sub-threshold slope is reduced due to the dominance of the tunneling component of the drive current. The simulation has been performed on a 100 nm channel length device although the fabrication has been carried out on micrometer scale transistors. The results of conventional Schottky and asymmetric devices have been compared both experimentally and numerically, confirming the significant improvement in our proposed structure. (C) 2009 Elsevier Ltd. All rights reserved.