Multiband coupling and electronic structure of (InAs){sub n}/(GaSb){sub n} superlattices
- National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
- Naval Research Laboratory, Washington DC 20375 (United States)
The electronic structure of abrupt (InAs){sub n}/(GaSb){sub n} superlattices is calculated using a plane wave pseudopotential method and the more approximate eight band {bold k}{center_dot}{bold p} method. The {bold k}{center_dot}{bold p} parameters are extracted from the pseudopotential band structures of the zinc-blende constituents near the {Gamma} point. We find, in general, good agreement between pseudopotential results and {bold k}{center_dot}{bold p} results, except as follows. (1) The eight band {bold k}{center_dot}{bold p} significantly underestimates the electron confinement energies for n{le}20. (2) While the pseudopotential calculation exhibits (a) a zone center electron-heavy hole coupling manifested by band anticrossing at n=28, and (b) a light hole{endash}heavy hole coupling and anticrossing around n=13, these features are absent in the {bold k}{center_dot}{bold p} model. (3) As {bold k}{center_dot}{bold p} misses atomistic features, it does not distinguish the C{sub 2v} symmetry of a superlattice with no-common-atom such as InAs/GaSb from the D{sub 2d} symmetry of a superlattice that has a common atom, e.g., InAs/GaAs. Consequently, {bold k}{center_dot}{bold p} lacks the strong in-plane polarization anisotropy of the interband transition evident in the pseudopotential calculation. Since the pseudopotential band gap is larger than the {bold k}{center_dot}{bold p} values, and most experimental band gaps are even smaller than the {bold k}{center_dot}{bold p} band gap, we conclude that to understand the experimental results one must consider physical mechanisms beyond what is included here (e.g., interdiffusing, rough interfaces, and internal electric fields), rather than readjust the {bold k}{center_dot}{bold p} parameters. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 362701
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 60, Issue 8; Other Information: PBD: Aug 1999
- Country of Publication:
- United States
- Language:
- English
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