Abstract

Advances in submicron semiconductor materials science in the early 1980s created and continues to drive interest in high field transport and the dynamical properties on subpicosecond time scales. When accelerated to high velocities, electrons may lose energy through a number of complex scattering processes. However, over short distances and time scales, differences in the energy versus momentum relaxation times lead to the prediction of an interesting phenomenon, that of velocity overshoot.^[1] This process has been extensively studied using photoconductive transients since the early 1980s, although the interpretation of the experimental results still remains an area of controversy.^[2-4] In particular, the high excess energies of the photoexcited carriers used in previous experiments and the internal space charge field due to separation of electrons and holes at high carrier densities can mask the observance of effects due to velocity overshoot.

© 1992 IQEC