G. Kioseoglou et al., Photoluminescence and reflectance studies of negatively charged excitons in GaAs/Al0.3Ga0.7As quantum-well structures, PHYS REV B, 61(7), 2000, pp. 4780-4785
We report the results of a systematic photoluminescence and reflectance stu
dy of negatively charged excitons (X-) in several GaAs/AlxGa1-xAs quantum w
ell structures. Samples are either doped n-type in the wells or not intenti
onally doped, and thus the appearance of X- (present in modulation doped sa
mples) is not expected. The combination of the two spectroscopies allowed u
s to explore the possible mechanisms responsible for the formation of the X
- complex, in all cases the X- signature is related to excess electrons in
the wells. These results provide positive evidence that the original identi
fication of the X- photoluminescence feature is correct.