Iue Annual Review 2004

Biography:
Viktor A. Sverdlov was born in 1963 in Leningrad, Russia. He received his Master of Science and Ph.D. degrees in physics from St.Petersburg State University (St.Petersburg, Russia) in 1985 and 1989, respectively. From 1989 to 1999 he worked as a staff research scientist at the V.A.Fock Institute of Physics, St.Petersburg State University. During this time, he actively visited leading European research centers and Universities: ICTP (Italy, 1993), University of Geneva (Switzerland, 1993-1994), University of Oulu (Finland,1995), Helsinki University of Technology (Finland, 1996, 1998), FU Berlin (Germany, 1997), NORDITA (Denmark, 1998). In 1999 he became a Staff Research Scientist at the State University of New York at Stony Brook. In April 2004 he joined the Institute for Microelectronics, Technische Universität Wien. His scientific interests include device simulation, computational physics, solid-state physics, and nanoelectronics.

The Wigner Monte Carlo Method for Semiconductor Device Simulation

Aggressive scaling of MOSFETs below 50 nm feature size makes the theoretical description and modeling of carrier transport in these devices challenging. The two major quantum effects to be taken into account are size quantization in the channel and quantum mechanical tunneling along the channel. Both effects call into question the use of powerful and well-developed simulation methods based on the semi-classical Boltzmann equation. Continued scaling of MOSFET feature size below 50nm requires the development and calibration of new simulation methods capable of incorporating the quantum effects properly. One of the promising approaches is the Wigner function method. The equation for the Wigner function describes both quantum interference and dissipation effects due to carrier scattering with equal accuracy. The Monte Carlo method is derived starting from the integral form of the Wigner-Boltzmann equation. The kernel of the adjoint equation is decomposed into a linear combination of conditional probability densities. The latter represents the transition density used for the construction of numerical trajectories.
The properties of the transition density allow a particle picture to be introduced. In this picture dissipation and interference phenomena are taken into account by two alternative processes involving particles. Interaction with the classical force field and with various scattering sources is taken into account by drift and scattering processes corresponding to the semi-classical Boltzmann transport picture. Quantum interference effects due to the Wigner potential are associated with a generation process of particle pairs carrying the statistical weights plus/minus one.

Results of simulations of the particle densities in the MOSFET using the semi-classical Boltzmann equation (classical) and fully quantum Wigner Monte Carlo approach (Wigner). Quantum effects play an important role leading to a substantial charge density increase in the potential barrier region due to additional density contribution of tunneling electrons.