Simulation at the Start of the New Millenium: Crossing the Quantum-Classical Threshold

It is clear that continued scaling of semiconductor devices will bring us to a regime withgate lengths less than 50nm within another decade. The questions that must beaddressed in simulation are difficult. Pushing to dimensional sizes such as this will probethe transition from classical to quantum transport, and there is no present approach tothis regime that has proved effective. Contrary to the classical case in which electrons arenegligibly small, the finite extent of the momentum space available to the electron setsize limitations on the minimum wave packet–this is of the order of a few nanometers–and leads to the effective potential. The latter is an approach to find theequivalent classical potential, by which the actual potential is modified by quantumeffects. The use of the effective potential for analyzing the effect of quantization onsemiconductor devices will be discussed. The manner in which this leads to newformulations for quantum transport will be discussed