Electron drift velocity in silicon

Experimental results for electrons obtained with the time-of-flight technique are presented for temperatures between 8 and 300^ and fields ranging between 1. 5 and 5 10^4 V cm^-1 oriented along 〈111〉, 〈110〉, and 〈100〉 crystallographic directions. At 8^ the dependence of the transit time upon sample thickness has allowed a measurement of the valley repopulation time when the electric field is 〈100〉 oriented. These experimental results have been interpreted with Monte Carlo calculations in the same ranges of temperature and field. The theoretical model includes the many-valley structure of the Si conduction band, acoustic intravalley scattering with correct momentum and energy relaxation and correct equilibrium phonon population, several intervalley scatterings, and ionized impurity scattering.