Fabian Cadiz has obtained a prize for his thesis of Ecole Polytechnique entitled "Spin dependent transport in semiconductors : a consequence of the Pauli Principle" and supported in July 2015. For this work, he has used an original technique consisting in injecting high concentrations of spin-polarized photoelectrons into a semiconductor and in studying the transport of these electrons and of their spin by polarized luminescence microimaging. The main result of his work is the fact that, at high concentration, the photelectron diffusion depends on their spin, and is a consequence of the Pauli Principle. The average diffusion constant also depends on their polarization. This result is an effect of the quantum pressure of the electron gaz, which depends on their average spin.