S. Wongmanerod et al., Magneto-optical studies of highly p-type modulation-doped GaAs/AlxGa1-xAs quantum wells, PHYS REV B, 62(23), 2000, pp. 15952-15961
We report on the optical properties of 150-Angstrom -wide p-type modulation
-doped quantum wells (QW's) with hole concentrations in the range of 0.7 x
10(12) - 3.1 x 10(12) cm(-2) under high applied magnetic fields up to 14 T.
The magnetoexciton is clearly observed in undoped QW's, but is affected by
the band mixing effect and finally quenched in the highly doped samples. T
he survival of the exciton up to a carrier concentration of 0.7 x 10(12) cm
(-2) is confirmed. The free carrier Landau level model including the valenc
e-band mixing effect and the conduction-band nonparabolicity can nicely des
cribe the electronic transitions in this doping regime. Moreover, the band-
gap renormalization is found to be insensitive to the magnetic field variat
ion. As a consequence, the values of interband transition energies together
with the corresponding many-body shifts are accurately evaluated. Finally,
an anomalous absorption feature near the Fermi edge is found to arise upon
the application of high magnetic fields. This transition is proposed to be
associated with a band-tail effect.