Valley degeneracies in (111) Si quantum wells
| Valley degeneracies in (111) Si quantum wells |
Neerav Kharche, Seongmin Kim, Timothy Boykin, Gerhard Klimeck |
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Objective:
- Resolve discrepancies in experimentally observed and theoretically predicted valley degeneracies
- Study effect of surface morphology on the electronic structure
Approach:
- Supercell tight-binding calculations to model surface miscuts
- Effective mass based valley-projection model to determine the directions of valley-minima of large supercells
Impact:
- Atomistic basis representation is essential to capture the effect of mono-atomic steps on the electronic structure
- Surface miscut of (111) Si is found to be the origin of breaking of 6 fold valley degeneracy into lower 2 fold and higher 4 fold valley degeneracies
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Results:
- Flat (111) Si QW shows 6 fold valley degeneracy
- Miscut causes 2-4 splitting due to different effective masses in confinement direction
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