Effect of strain on a second-order van Hove singularity in AlxGa1-xAs/InyGa1-yAs quantum wells
We have performed low-temperature photoluminescence and photoluminescence excitation (PLE) measurements on highly degenerate p-type GaAs and InyGa1−yAs quantum wells. In the PLE spectrum of the GaAs well, evidence of a second-order van Hove singularity in the joint density of states of the ground-st...
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| Hauptverfasser: | , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
15 October 1996
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| In: |
Physical review. B, Condensed matter and materials physics
Year: 1996, Jahrgang: 54, Heft: 15, Pages: 10644-10651 |
| ISSN: | 1550-235X |
| DOI: | 10.1103/PhysRevB.54.10644 |
| Online-Zugang: | Verlag, Volltext: https://doi.org/10.1103/PhysRevB.54.10644 Verlag, Volltext: https://link.aps.org/doi/10.1103/PhysRevB.54.10644 
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| Verfasserangaben: | M. Kemerink, P.M. Koenraad, and J.H. Wolter |
| Zusammenfassung: | We have performed low-temperature photoluminescence and photoluminescence excitation (PLE) measurements on highly degenerate p-type GaAs and InyGa1−yAs quantum wells. In the PLE spectrum of the GaAs well, evidence of a second-order van Hove singularity in the joint density of states of the ground-state light-hole and electron bands is found. This singularity results from the equality of ground-state light-hole and electron effective masses near the Γ point, being a much more restrictive demand than the usual condition for a van Hove singularity, which requires only the equality of first derivatives of the subband dispersions. The second-order van Hove singularity gives rise to a power-law divergence at the singular point, whereas the corresponding usual van Hove singularity results in a steplike discontinuity in the joint density of states. The observed singularity could be described extremely well by a simple analytical model. The increased energy gap between light- and heavy-hole ground states in the compressively strained InyGa1−yAs well enhances the valence-band parabolicity, resulting in the disappearance of the van Hove singularity. Furthermore, it is shown that the anisotropic character of the heavy-hole ground state in GaAs is strongly suppressed in the InyGa1−yAs system. All experiments are in good agreement with our numerical modeling, based on an exact solution of the 4×4 Luttinger Hamiltonian. © 1996 The American Physical Society. |
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| Beschreibung: | Im Titel sind "x", "1-x", "y" und "1-y" tiefgestellt Gesehen am 10.12.2019 |
| Beschreibung: | Online Resource |
| ISSN: | 1550-235X |
| DOI: | 10.1103/PhysRevB.54.10644 |