  Measurements of the drift velocities of electrons and holes as functions of
electric field and temperature in high-purity n- and p-type silicon with <100>
orientation are presented. The measurements cover electric field values between
2.5 and 50 kV/cm and temperatures between 233 and 333 K. For both electrons and
holes differences of more than 15 % are found between our <100> results and the
<111> drift velocities from literature, which are frequently also used for
simulating <100> sensors. For electrons, the <100> results agree with previous
<100> measurements, however, for holes differences between 5 to 15 % are
observed for fields above 10 kV/cm. Combining our results with published data
of low-field mobilities, we derive parametrizations of the drift velocities in
high-ohmic <100> silicon for electrons and holes for fields between 0 and 50
kV/cm, and temperatures between 233 and 333 K. In addition, new
parametrizations for the drift velocities for electrons and holes are
introduced, which provide somewhat better descriptions of existing data for
<111> silicon, than the standard parametrization.
