Dipole matrix elements and the nature of charge oscillation under coherent interband excitation in quantum wells

Coles, RA; Abram, RA; Brand, S; Burt, MG

Abstract

An empirical pseudopotential method is used to model two type-I quantum-well systems, allowing the investigation of interband dipole-matrix elements and charge oscillation under coherent optical excitation. Each relevant (microscopically varying) wave function is expressed as an exact envelope-function expansion to which various approximations are made, in analogy with envelope-function methods such as the k⋅p model. The approximation to the quantum-well energy eigenfunctions of a single envelope function multiplying a band-edge zone-center state, the “atomic picture,” is shown to underestimate by orders of magnitude the interband dipole-matrix element. Including terms due to the second band edge, which play only a minor role in the exact envelope-function expansion, provides a good approximation to the true dipole-matrix element, which is significantly greater than the atomic picture predicts. In addition, the effect on the interband charge oscillation of omitting the second band-edge terms is shown to be a reduction of the oscillation from the width of the well to the atomic scale. These results confirm that the earlier results of Burt hold for realistic three-dimensional systems.

Citation

Coles, R., Abram, R., Brand, S., & Burt, M. (1999). Dipole matrix elements and the nature of charge oscillation under coherent interband excitation in quantum wells. Physical review B, 60(19), 13306-13309. https://doi.org/10.1103/physrevb.60.13306

• Journal Article Type: Article
• Publication Date: Nov 1, 1999
• Deposit Date: Dec 7, 2010
• Publicly Available Date: Dec 8, 2010
• Journal: Physical review B - Condensed Matter and Materials Physics
• Print ISSN: 1098-0121
• Electronic ISSN: 1550-235X
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 60
• Issue: 19
• Pages: 13306-13309
• DOI: https://doi.org/10.1103/physrevb.60.13306
• Public URL: https://durham-repository.worktribe.com/output/1619804
• Publisher URL: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999PhRvB..6013306C&db_key=PHY