The silicon MOSFET from a transmission viewpoint

Landauer's view of conductance as a process of transmission has had a profound influence on basic transport physicists but is relatively unappreciated by device engineers. In this paper we draw attention to the new insights and perspectives that the transmission viewpoint can provide into the design of deep submicron MOSFETs. Firstly, we show that there is a fundamental limit to the minimum contact resistance (similar to 300 Omega-mu m under moderate gate bias and similar to 50 Omega-mu m under high gate bias) that no amount of contact technology can overcome and that present day devices are close to this fundamental limit. Secondly we show that the saturation drain current is determined by the transmission coefficient which depends sensitively on the electric field within a mean free path of the source. Present day devices have transmission coefficients similar to 50% which could be increased by increasing the electric field at the source. But the improvement is limited by the increase in quantum mechanical reflections. (C) 1998 Academic Press Limited.