Quasiparticle band offset at the (001) interface and band gaps in ultrathin superlattices of GaAs-AlAs heterojunctions
1990; American Physical Society; Volume: 41; Issue: 14 Linguagem: Inglês
10.1103/physrevb.41.10058
ISSN1095-3795
AutoresShengbai Zhang, Marvin L. Cohen, Steven G. Louie, David Tománek, Mark S. Hybertsen,
Tópico(s)Semiconductor Quantum Structures and Devices
ResumoA newly developed first-principles quasiparticle theory is used to calculate the band offset at the (001) interface and band gaps in 1\ifmmode\times\else\texttimes\fi{}1 and 2\ifmmode\times\else\texttimes\fi{}2 superlattices of GaAs-AlAs heterojunctions. We find a sizable many-body contribution to the valence-band offset which is dominated by the many-body corrections to bulk GaAs and AlAs quasiparticle energies. The resultant offset \ensuremath{\Delta}${\mathit{E}}_{\mathit{v}}$=0.53\ifmmode\pm\else\textpm\fi{}0.05 eV is in good agreement with the recent experimental values of 0.50--0.56 eV. Our calculated direct band gaps for ultrathin superlattices are also in good agreement with experiment. The ${\mathit{X}}_{1\mathit{c}}$-derived state at point \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{}, is however, above the ${\mathrm{\ensuremath{\Gamma}}}_{1\mathit{c}}$-derived state for both the 1\ifmmode\times\else\texttimes\fi{}1 and 2\ifmmode\times\else\texttimes\fi{}2 lattices, contrary to results obtained under the virtual-crystal approximation (a limiting case for the Kronig-Penny model) and some previous local-density-approximation (corrected) calculations. The differences are explained in terms of atomic-scale localizations and many-body effects. Oscillator strengths and the effects of disorder on the spectra are discussed.
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