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 with gate lengths less than 50nm within another decade. The questions that must be addressed in simulation are difficult. Pushing to dimensional sizes such as this will probe the transition from classical to quantum transport, and there is no present approach to this regime that has proved effective. Contrary to the classical case in which electrons are negligibly small, the finite extent of the momentum space available to the electron set size 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 the equivalent classical potential, by which the actual potential is modified by quantum effects. The use of the effective potential for analyzing the effect of quantization on semiconductor devices will be discussed. The intoner in which this leads to new formulations for quantum transport will be discussed.