  The heat transport in heavy-doped n-GaAs has been investigated at
temperatures T=300 K and 77 K using the irradiation of the metal-semiconductor
contact by modulated CO_{2}-laser radiation. It is shown this approach giving
an opportunity to determine the thermo-diffusion coefficient $\chi$ and Seebeck
coefficient S_{T} without direct measurements of the temperature gradient. It
was also found out that the thermalization length of hot electrons exceeds in
of order of magnitude the assessment which can be done based on the reference
data for GaAs. To elucidate the origin of the observed phenomenon the
measurements were conducted out with Schottky contacts made on the thin doped
GaAs layer epitaxially grown on the semi-insulating GaAs substrate. In this
case the degenerate electron gas occupies only insignificant part of the
heat-conducting medium. In addition, the injection of hot electrons into the
semiconductor by current pulses through the Schottky barrier was used to clear
up whether there is a dependence of the effect on the method of the electron
heating. The nonequilibrium of LO-phonons and the change in the electron-phonon
collisional integral due to the non-equilibrium pair correlations of the
electrons are suggested as a possible explanation.
