The blue photoluminescence and nanostructure of Si and C clusters embedded in SiO2 matrices

Zhang, Q.; Bayliss, S. C.; Al-Ajili, A.; Hutt, D.A.; Harris, Peter

doi:10.1016/0168-583x(94)00727-6

Cited by 14 publications

(7 citation statements)

References 13 publications

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“…[29][30][31] These studies are consistent with an interpretation that the blue emission is associated with Si oxides and that the orange PL is particle size dependent and derives from the quantum confinement effect in Si. Blue emission has been observed from Si and C implanted in SiO 2 matrices 32 and from carbon-plasma-implanted porous silicon, 33 but the orange emission of porous silicon disappeared after implantation. There are at least two plausible reasons for the observation of two emission bands.…”

mentioning

confidence: 99%

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Chao

Houlton

Horrocks

et al. 2006

Applied Physics Letters

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The origin and stability of luminescence are critical issues for Si nanocrystals which are intended for use as biological probes. The optical luminescence of alkyl-monolayer-passivated silicon nanocrystals was studied under excitation with vacuum ultraviolet photons ͑5.1-23 eV͒. Blue and orange emission bands were observed simultaneously, but the blue band only appeared at low temperatures ͑Ͻ175 K͒ and with high excitation energies ͑Ͼ8.7 eV͒. At 8 K, the peak wavelengths of the emission bands were 430± 2 nm ͑blue͒ and 600± 2 nm ͑orange͒. The orange and blue emissions originate from unoxidized and oxidized Si atoms, respectively. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2216911͔Silicon nanostructures have attracted great interest since the observation of their efficient visible photoluminescence at room temperature in the early 1990s. 1-4 Silicon nanocrystals ͑SiNCs͒ are potential building blocks of future electronic and photonic devices. They also have promise as luminescent labels in biological applications, 5-9 because they show red-orange luminescence at small particle sizes ͑ca. 2 nm diam͒ and are not expected to show some aspects of the toxicity of cadmium-based semiconductors. However, the stability of SiNCs towards O 2 and H 2 O is a concern. Recently, several groups, including ourselves, have prepared alkyl-passivated silicon nanocrystals. [5][6][7][8][9][10][11][12][13][14][15][16] These are SiNCs whose surface is capped by a monolayer of saturated hydrocarbon molecules and anchored to the Si core via covalent Si-C bonds. Although the particles contain a little oxide from their preparation, the alkyl monolayer protects the Si core and they are not oxidized further under ambient conditions. 6 The reaction used to prepare the capping monolayer is sufficiently general to allow manipulation of the chemical functionality on the particle surface, e.g., for synthesis of DNA strands. 6 However, it is also important to characterize the physical properties, especially the luminescence, of these systems because the utility of the particles depends on their luminescence upon insertion into biological cells.Compared to the generally weak IR luminescence of bulk silicon ͑observed at low temperatures͒, the efficiency of photoluminescence ͑PL͒ from Si nanostructures is strongly increased due to the greater overlap of the electron and hole wave functions and the decrease in efficiency of nonradiative pathways. 17,18 A few electronic structure calculations on alkylated SiNCs have been made using density functional methods: these calculations include Si 29 clusters passivated with CH 3 or CH 2 ͑Ref. 19͒ and, more recently, alkyl monolayers up to C 4 H 9 on cluster sizes from Si 20 to Si 142 . 20 Theoretical work suggests that the band gap of SiNCs is little changed upon alkylation of the hydrogen-terminated particle surface, but the positions of the band edges are shifted significantly towards the vacuum level and the properties of the excited states are affected. 20 Experimental studies of the PL mechanism o...

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mentioning

confidence: 99%

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Chao

Houlton

Horrocks

et al. 2006

Applied Physics Letters

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“…These studies are consistent with an interpretation that the blue emission is associated with Si oxides and that the orange PL is particle sizedependent and derives from the quantum-confinement effect in Si. Blue emission has been observed from Si and C implanted in SiO 2 matrices [52] and from carbon-plasma-implanted porous silicon, [53] but the orange emission of porous silicon disappeared after implantation. There are at least two plausible reasons for the observation of two emission bands.…”

Section: Origin Of the Orange And Blue Pl Emissionmentioning

confidence: 99%

Optical Properties of Nanostructured Silicon

Chao

2011

Comprehensive Nanoscience and Technology

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“…On annealing at 800 "C for 20 to 30 min in a N, atmosphere the films were found to emit in the blue or blue-green, and this emission was visible to the naked eye under excitation by ~0 . 5 pW of 300 nm (or 3 pW of 370 nm) [7]: The tuneable excitation used for PLE was the ultraviolet radiation from the Daresbury Laboratory synchrotron source, where the bandwidth was = 10 nm.…”

Section: Sample Preparationmentioning

confidence: 99%

“…The resistivity and dopant type of the substrate wafers were also varied. Generally the ammonium and nitric etches produced material which emitted red-orange [6], whereas red, yellow, or green emission was obtained from samples anodised in H F [4, 51. Silicon clustered samples were prepared by rf co-sputtering from a SiO, target on which pieces of elemental Si had been placed.…”

Section: Sample Preparationmentioning

confidence: 99%

“…We present here a comparison of the local structures of two such systems: firstly porous silicon, produced by several processes, and secondly silicon clusters embedded in silicon oxide, important because of their stability. Both systems show visible PL, porous silicon emitting from red to green [4 to 61, and the clustered matrices emitting in the blue-green and blue [7]. We have concentrated on the local structure to find out any similarities in the chemistry or disorder in these systems, in order to understand more about the environment which produces the efficient PL.…”

Section: Introductionmentioning

confidence: 99%

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From Porous Silicon to Clustered Matrices: A Comparison of Local Structures

Bayliss

Zhang

Hutt

1995

Physica Status Solidi (b)

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(Received M a y 22, 1995)Studies have been made of the local atomic structure ofclustered and porous silicon nanostructures, with the object of obtaining more information on the environments which exist in highly PL-efficient material. In some structures the Si environments can be interpreted in terms of a small crystalline core surrounded by configurationally disordered material. Finally, although the details of the individual mechanisms responsible for the emission appear to be different for clustered and porous material, the overall behaviour can be linked t o the sizes and dimensionality of the units involved.

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The blue photoluminescence and nanostructure of Si and C clusters embedded in SiO2 matrices

Cited by 14 publications

References 13 publications

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Optical Properties of Nanostructured Silicon

From Porous Silicon to Clustered Matrices: A Comparison of Local Structures

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