  We study the spatial distribution of minority carriers arising from their
anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP
slab for temperatures ranging from 300 K to 78 K. The experiment provides a
realization of the "L\'evy flight" random walk of holes, in which the L\'evy
distribution index gamma is controlled by the temperature. We show that the
variation \gamma(T) is close to that predicted earlier on the basis of the
assumed quasi-equilibrium (van Roosbroek-Shockley) intrinsic emission spectrum,
\gamma=1-\Delta /kT, where \Delta(T) is the Urbach tailing parameter of the
absorption spectra. The decreasing \gamma at lower temperatures results in a
giant enhancement in the spread of holes -- over distances exceeding 1 cm from
the region of photo-excitation.
