Optical gaps of free and embedded Si nanoclusters: Density functional theory calculations

Timothy J. Pennycook, George Hadjisavvas, Juan C. Idrobo, Pantelis C. Kelires, and Sokrates T. Pantelides

Phys. Rev. B 82, 125310 – Published 9 September 2010

Abstract

The optical gaps of free and embedded Si nanoclusters are studied within the time-dependent local-density approximation. The effects of deformation, the bonding of individual O atoms on the surface, and coverage by ${SiO}_{2}$ layers on the highest occupied molecular orbital-lowest unoccupied molecular orbital and optical gaps are systematically compared. It is found that all three can have a significant impact. Oxygen bonded to the surface and deformation cause the greatest reduction in the gaps, particularly in combination.

Received 5 May 2010

DOI:https://doi.org/10.1103/PhysRevB.82.125310

Authors & Affiliations

Timothy J. Pennycook^1,2,*, George Hadjisavvas³, Juan C. Idrobo^1,2, Pantelis C. Kelires³, and Sokrates T. Pantelides^1,2

¹Department of Physics & Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
²Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
³Department of Mechanical and Materials Science Engineering, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol, Cyprus

^*t.pennycook@vanderbilt.edu

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Vol. 82, Iss. 12 — 15 September 2010

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Physical Review B

covering condensed matter and materials physics