Magnetic-field-induced indirect gap in a modulation-doped quantum well

We report the first experimental evidence for the indirect fundamental band gap developed when an in-plane magnetic field is applied to a modulation-doped quantum well. The observed photoluminescence peak for the lowest subband undergoes a large, approximately quadratic shift with field, a consequence of the behavior of the allowed transitions in the increasingly indirect-gap band-structure. A good theoretical fit is obtained by calculating the transition energies using a realistic self-consistent Hartree potential for the quantum-well profile.