Study of the directhyphen;indirect bandhyphen;gap transition in GaAs/AlAs shorthyphen;period superlattices using photocurrent spectroscopy

摘要

We have unambiguously shown that lowhyphen;energy optical transitions generate electrons that belong either to the Ggr; minimum of GaAs or to theXminimum of AlAs, depending on the mean aluminum concentration, for a series of 5hyphen;nm period GaAs/AlAs superlattices. We estimate the intensity of the potential responsible for the Ggr;hyphen;Xmixing to be on the order of 1ndash;2 meV. For this kind of study, the photocurrent technique, which gives wellhyphen;structured spectra recorded on large spectral (bartil;0.7 eV) and temperature (4ndash;300 K) ranges, appears more favorable than the photoluminescence excitation spectroscopy technique.