  Here, we analyze in a non-contact fashion charge carrier mobility as a
function of injection level and temperature in silicon by time resolved THz
spectroscopy (TRTS) and parametrize our data by the classical semi-empirical
models of Klaassen and Dorkel & Leturcq. Our experimental results are in very
good agreement with the pioneering works of Krausse and D\"annhauser analyzing
this phenomena by employing contact-based methods. This agreement, that
validates our methodology, can only be achieved by considering charge carrier
diffusion effects following above bandgap near-surface pump photo-excitation of
the sample. From our results, obtained over a large range of injection levels,
we conclude that the model of Klaassen is the best on describing the collected
data at room temperature. Furthermore, we analyze by TRTS the dependence of
charge carrier mobility with temperature for a fixed injection level. Once
more, the parametrization made by the classical model of Klaassen describe our
data appropriately even without the necessity of applying any fitting
parameters (just with the charge carrier density as an input). In this respect,
our work supports the validity of the model and parametrization proposed by
Klaassen, and also illustrate how TRTS can be reliably employed for the
quantitative determination of mobility in semiconductors as a function of key
parameters as injection level and temperature.
