  The effect of alloy disorder on the optical density of states and the average
room temperature carrier statistics in GaInNAs quantum wells is discussed. A
red shift between the peak of the room temperature photoluminescence and the
surface photovoltage spectra, that systematically increases with the nitrogen
content within the quantum wells is observed. The relationship between this
Stokes' shift and the absorption linewidth in different samples suggests that
the photoexcited carriers undergo a continuous transition, from being in
quasi-thermal equilibrium with the lattice to being completely trapped by the
quantum dot-like potential fluctuations, as the nitrogen fraction in the alloy
is increased. The values of the 'electron temperature' inferred from the
photoluminescence spectra are found to be consistent with this interpretation.
