We present first principle calculations of ultrathin silicon (111) layers embedded in CaF2, a lattice matched insulator. Our all electron calculation allows a check of the quantum confinement hypothesis for the Si band gap opening as a function of thickness. We find that the gap opening is mostly due to the valence band while the lowest conduction band states shift very modestly due to their pronounced interface character. The latter states are very sensitive to the sample design. We suggest that a quasidirect band gap can be achieved by stacking Si layers of different thickness.
GAP OPENING IN ULTRATHIN SI LAYERS - ROLE OF CONFINED AND INTERFACE STATES / Ossicini, Stefano; A., Fasolino; F., Bernardini. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 72:(1994), pp. 1044-1047.
GAP OPENING IN ULTRATHIN SI LAYERS - ROLE OF CONFINED AND INTERFACE STATES
OSSICINI, Stefano;
1994
Abstract
We present first principle calculations of ultrathin silicon (111) layers embedded in CaF2, a lattice matched insulator. Our all electron calculation allows a check of the quantum confinement hypothesis for the Si band gap opening as a function of thickness. We find that the gap opening is mostly due to the valence band while the lowest conduction band states shift very modestly due to their pronounced interface character. The latter states are very sensitive to the sample design. We suggest that a quasidirect band gap can be achieved by stacking Si layers of different thickness.Pubblicazioni consigliate
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