The role of silicon oxide layers in luminescence of ensembles of silicon quantum dots

Citation
Sh. Wang et al., The role of silicon oxide layers in luminescence of ensembles of silicon quantum dots, COMM TH PHY, 35(3), 2001, pp. 371-380
Citations number
21
Categorie Soggetti
Physics
Journal title
COMMUNICATIONS IN THEORETICAL PHYSICS
ISSN journal
02536102 → ACNP
Volume
35
Issue
3
Year of publication
2001
Pages
371 - 380
Database
ISI
SICI code
0253-6102(20010315)35:3<371:TROSOL>2.0.ZU;2-H
Abstract
Based on the quantum confinement-luminescence center model, to ensembles of spherical silicon nanocrystals (nc-Si) containing two kinds of luminescenc e centers (LCs) in the SiOinfinity layers surrounding the nc-Si, the relati onship between the photoluminescence (PL) and the thickness of the SiOinfin ity layer is studied with the excitation energy flux density as a parameter . When there is no SiOinfinity layer surrounding the nc-Si, the electron-he avy hole pair can only recombine inside the nc-Si, then the PL blueshift wi th reducing particle sizes roughly accords with the rule predicted by the q uantum confinement model of Canham. When there presences a SiOinfinity laye r, some of the carriers may tunnel into it and recombine outside the nc-Si at the LCs to emit visible light. The thicker the SiOinfinity layer is, the higher the radiative recombination rate occurred outside the nc-Si will be . When the central scale of the nc-Si is much smaller than the critical sca le, the radiative recombination rate outside the nc-Si dominates, and visib le PL will be possible for some nc-Si samples with big average radius, grea ter than 4 nm, for example. When there is only one kind of LC in, the SiOin finity layer, the PL peak position does not shift with reducing particle si zes. All these conclusions are in accord with the experimental results. Whe n there are two or more kinds of LCs in the SiOinfinity layer, the PL peak position energy and intensity swing with reducing particle sizes.