Direct bandgap silicon: tensile-strained silicon nanocrystals

0436758 - FZÚ 2015 RIV DE eng J - Journal Article
Kůsová, Kateřina - Hapala, Prokop - Valenta, J. - Jelínek, Pavel - Cibulka, Ondřej - Ondič, Lukáš - Pelant, Ivan
Direct bandgap silicon: tensile-strained silicon nanocrystals.
Advanced Materials Interfaces. Roč. 1, č. 2 (2014), "1300042-1"-"1300042-9". ISSN 2196-7350. E-ISSN 2196-7350
R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GPP204/12/P235; GA ČR GAP204/10/0952
Institutional support: RVO:68378271
Keywords : silicon nanocrystals * badstructure * light emission * direct bandgap * surface capping
Subject RIV: BM - Solid Matter Physics ; Magnetism

In this article, we show that silicon nanocrystals can be transformed into a material with fundamental direct bandgap via a concerted action of quantum confinement and tensile strain. We document this transformation by DFT calculations mapping the E(k) band-structure of Si nanocrystals. The experimental proofs are then given firstly by a 10 000× increase in the photon emission rate of strained silicon nanocrystals together with their altered absorbance spectra, both of which point to direct dipole-allowed transitions, secondly by single nanocrystal spectroscopy, confirming reduced phonon energies and thus the presence of tensile strain, and lastly by photoluminescence studies under external hydrostatic pressure.
Permanent Link: http://hdl.handle.net/11104/0240439