Effect of the Pauli principle on photoelectron spin transport in p⁺ GaAs

In p⁺ GaAs thin films, under excitation by a tightly-focussed laser, the spatial profile of the spin polarization is monitored as a function of excitation power. It is found that photoelectron diffusion depends on spin, as a direct consequence of the Pauli principle which causes a concentration dependence of the spin stiffness. Thermoelectric currents are also predicted to depend on spin under degeneracy (spin Soret currents), but these currents play a relatively small role in this case. The spin dependence of the mobility is also found weak. Conversely, ambipolar coupling with holes increases the steady-state photo-electron density at the place of excitation and therefore the amplitude of the degeneracy-induced polarization decrease at the place of excitation.