Abstract
We report direct measurements of changes in the conduction-band structure of ultrathin silicon nanomembranes with quantum confinement. Confinement lifts the 6-fold-degeneracy of the bulk-silicon conduction-band minimum (CBM), Δ, and two inequivalent sub-band ladders, Δ2 and Δ4, form. We show that even very small surface roughness smears the nominally steplike features in the density of states (DOS) due to these sub-bands. We obtain the energy splitting between Δ2 and Δ4 and their shift with respect to the bulk value directly from the 2p3/2→Δ transition in X-ray absorption. The measured dependence of the sub-band splitting and the shift of their weighted average on degree of confinement is in excellent agreement with theory, for both Si(001) and Si(110).
Original language | English (US) |
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Pages (from-to) | 2466-2474 |
Number of pages | 9 |
Journal | ACS Nano |
Volume | 4 |
Issue number | 4 |
DOIs | |
State | Published - Apr 27 2010 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- General Materials Science
- General Engineering
- General Physics and Astronomy
Keywords
- Quantum confinement
- Silicon nanomembrane
- Surface roughness
- Thermoelectric
- Valley splitting