Photoluminescence spectra of {ital n}-doped double quantum wells in a parallel magnetic field
- Air Force Research Laboratory (AFRL/VSSS), Kirtland Air Force Base, New Mexico 87117 (United States)
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
We show that the photoluminescence (PL) line shapes from tunnel-split ground sublevels of {ital n}-doped thin double quantum wells (DQW{close_quote}s) are sensitively modulated by an in-plane magnetic field B{sub {parallel}} at low temperatures (T). The modulation is caused by the B{sub {parallel}}-induced distortion of the electronic structure. The latter arises from the relative shift of the energy-dispersion parabolas of the two quantum wells (QW{close_quote}s) in {rvec k} space, both in the conduction and valence bands, and formation of an anticrossing gap in the conduction band. Using a self-consistent density-functional theory, the PL spectra and the band-gap narrowing are calculated as a function of B{sub {parallel}}, {ital T}, and the homogeneous linewidths. The PL spectra from symmetric and asymmetric DQW{close_quote}s are found to show strikingly different behavior. In symmetric DQW{close_quote}s with a high density of electrons, two PL peaks are obtained at B{sub {parallel}}=0, representing the interband transitions between the pair of the upper (i.e., antisymmetric) levels and that of the lower (i.e., symmetric) levels of the ground doublets. As B{sub {parallel}} increases, the upper PL peak develops an N-type kink, namely a maximum followed by a minimum, and merges with the lower peak, which rises monotonically as a function of B{sub {parallel}} due to the diamagnetic energy. When the electron density is low, however, only a single PL peak, arising from the transitions between the lower levels, is obtained. In asymmetric DQW{close_quote}s, the PL spectra show mainly one dominant peak at all B{sub {parallel}}{close_quote}s. In this case, the holes are localized in one of the QW{close_quote}s at low {ital T} and recombine only with the electrons in the same QW. At high electron densities, the upper PL peak shows an N-type kink like in symmetric DQW{close_quote}s. However, the lower peak is absent at low B{sub {parallel}}{close_quote}s because it arises from the inter-QW transitions. Reasonable agreement is obtained with recent data from GaAs/Al{sub 0.3}Ga{sub 0.7}As DQW{close_quote}s. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 321983
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 59, Issue 11; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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