Study of the single-particle and transport lifetimes in GaAs/AlxGa

Abstract

We report a large discrepancy between the measured and theoretically predicted Fermi wave-vector dependence of the transport lifetime to single-particle lifetime ratio for a modulation-doped GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As heterostructure when the carrier density is varied by thermally cycling the sample, grown using molecular-beam epitaxy (MBE), after illumination by a light pulse. The results suggest that the deep centers responsible for the persistent photoconductivity effect, which may originate from nonstoichiometric MBE growth, are the dominant factor in limiting the single-particle lifetime in GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As.