Γ-Xmixing in GaAs/AlxGa1−xAs coupled double quantum wells under hydrostatic pressure
| Autor: | Hyeonsik Cheong, B. Elman, E.S. Koteles, William Paul, J. H. Burnett |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Physical Review B. 47:1991-1997 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.47.1991 |
| Popis: | We have investigated the energies of the electronic states of GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As strongly coupled double quantum wells and uncoupled multiple quantum wells as functions of hydrostatic pressure up to 35 kbar. The energies of the quantum-well states at 4 K were determined at each pressure by photoluminescence excitation spectra. The pressure coefficients of the energies of the allowed transitions between the valence-band and conduction-band quantized states of wide (200 \AA{}) uncoupled wells were all equal to the pressure coefficient of the bulk GaAs band gap. For a strongly coupled double quantum well consisting of two 72-\AA{} wells separated by an 18-\AA{} barrier, the energies of the allowed transitions all showed a decrease in their pressure coefficients beginning near 20 kbar. These results are interpreted in terms of a drop in the conduction-band quantum-well confinement energy, due to \ensuremath{\Gamma}-X mixing, as the X valleys of the barrier materials are brought nearly equal to the energies of the confined electron states by pressure. An envelope-function-approximation model which includes \ensuremath{\Gamma}-X mixing at the interfaces is compared quantitatively with these results and found to be consistent for a certain range of the phenomenological mixing strength of the model. |
| Databáze: | OpenAIRE |
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