Photoluminescence studies of modulation doped coupled double quantum wells in magnetic fields

摘要

We have studied the photoluminescence spectra of a series of mudulation doped couple double quantum well structures in parallel and perpendicular magnetic fields to 62 tesla at 4K and 77K, for B(parallel)a, the spectra display distinct Landau level transitions which show anti-crossing with the e1-hh1 exciton. At high fields, the lowest conduction band-valence exciton approaches the extrapolated 0-0 Landau level. About 25 Tesla, there is valence band mixing of the e1-lh1, e1-hh2, e1-hh1 transitions. The spectral peaks display a diamagnetic shift in low in-plane magnetic fields which become linear in high fields. At magnetic fields beyond 40T, spin splitting is observed for both B(parallel)z and B(perpendicular) geometries. The partial energy gap discovered in conductance measurements in in-plane fields was not conclusively observed using photoluminescence spectroscopy, although anomalies in the energy dependence of the lowest level with magnetic field were evident at similar field values.