Electron drift velocity in silicon

Experimental results for electrons obtained with the time-of-flight technique are presented for temperatures between 8 and 300\ifmmode^\circ\else\textdegree\fi{}K and fields ranging between 1.5 and 5 \ifmmode\times\else\texttimes\fi{} ${10}^{4}$ V ${\mathrm{cm}}^{\ensuremath{-}1}$ oriented along $〈111〉$, $〈110〉$, and $〈100〉$ crystallographic directions. At 8\ifmmode^\circ\else\textdegree\fi{}K 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.