Subpicosecond transient Raman spectroscopy has been used to study electron transport properties of
an In0.53Ga0.47As
based p–i–n nanostructure. Both the electron distribution function and the electron drift
velocity have been directly measured as a function of the photoexcited electron–hole
pair density. We have found that, at low electron–hole pair densities such as
n = 5 × 1016 cm−3, the electron distribution function has an extremely non-Maxwellian shape. However, as
the photoexcited electron pair density gradually increases, the non-Maxwellian distribution
gradually evolves into a shifted Maxwellian distribution. We attribute these findings to the
direct effects of the role of electron–electron scattering in momentum randomization.