Lattice-mismatch induced-stress in porous silicon films

Manotas, S.; Agulló-Rueda, F.; Moreno, José David; Ben-Hander, F.; Martı́nez-Duart, J.M.

doi:10.1016/s0040-6090(01)01641-8

Cited by 56 publications

(30 citation statements)

References 13 publications

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“…Stress on silicon nanocrystals induces a peak shift in the Raman spectrum and the absolute size dependent shift can only be determined by eliminating the stress-related shift. The origin of the stress is reported as 35 the lattice mismatch between the silicon nanostructure and the host matrix. Figure 4(a) demonstrates the characteristic (111) XRD diffraction peak of crystalline silicon centered at 2h ¼ 28.4 .…”

Section: Resultsmentioning

confidence: 99%

Direct characterization of nanocrystal size distribution using Raman spectroscopy

Doğan

Sanden

2013

Journal of Applied Physics

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We report a rigorous analytical approach based on one-particle phonon confinement model to realize direct detection of nanocrystal size distribution and volume fraction by using Raman spectroscopy. For the analysis, we first project the analytical confinement model onto a generic distribution function, and then use this as a fitting function to extract the required parameters from the Raman spectra, i.e., mean size and skewness, to plot the nanocrystal size distribution. Size distributions for silicon nanocrystals are determined by using the analytical confinement model agree well with the one-particle phonon confinement model, and with the results obtained from electron microscopy and photoluminescence spectroscopy. The approach we propose is generally applicable to all nanocrystal systems, which exhibit size-dependent shifts in the Raman spectrum as a result of phonon confinement.

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Section: Resultsmentioning

confidence: 99%

Direct characterization of nanocrystal size distribution using Raman spectroscopy

Doğan

Sanden

2013

Journal of Applied Physics

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“…The reason for strong influence of compressive stress on the peak position of TO vibrational band, in freshly etched samples, may be in different etching rate between the epitaxial and the substrate layer. According to literature, 16 the stress in porous silicon is the strongest at the interface between the porous layer and the bulk silicon, and it is decreasing with distance from the interface. In these samples the etching process stops at the interface between two layers with different dopant concentration, and since the epitaxial layer was etched through and the etching of substrate has begun, the resulting porous silicon layer would be maximally 5-7 μm thick.…”

Section: Resultsmentioning

confidence: 95%

“…On the other hand, as the porosity of samples is increased, the compressive stress, caused by a lattice size discrepancy between porous and bulk silicon, is increased, too. 15,16 The increase in the internal compressive stress would cause the shift in the peak position of the TO band towards the higher wave numbers. Consequently, it may compensate the effect of nanocrystallite size reduction.…”

Section: Resultsmentioning

confidence: 99%

“…Since the infrared spectra (Figure 1a) show that freshly etched samples were not oxidized, and since it is known that in non oxidized porous silicon the threshold porosity is needed for efficient PL, 4 the absence of PL spectra leads to conclusion that all prepared samples have relatively low porosity. 16 On the other hand it is also possible that, due to the discontinuity in the etching process, the concentration of nonradiative recombination centres, like dangling bonds, was high and that they quenched photoluminescence. After the oxidation, the dangling bonds might become saturated with oxygen which act as radiative recombination centres and increase the intensity of photoluminescence as especially is strong for the sample S1 (Figure 4).…”

Section: Resultsmentioning

confidence: 99%

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Micro and Nano Structure of Electrochemically Etched Silicon Epitaxial Wafers

Gamulin¹,

Balarin²,

Ivanda³

et al. 2012

Croat. Chem. Acta

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Abstract. Silicon epitaxial wafers, consisting of 280 μm thick n-type substrate layer and 4-5 μm thick epitaxial layer, were electrochemically etched in hydrofluoric acid ethanol solution, to produce porous silicon samples. The resistivity of epitaxial layer was 1 Ω cm, while the substrate was much better conductor with resistivity 0.015 Ω cm. By varying the etching time, the micro-and nano-pores of different sizes were obtained within the epitaxial layer, and on the substrate surface. Due to the lateral etching the epitaxial layer was partially detached from the substrate and could be peeled off. The influence of etching time duration on the optical and structural properties of porous samples was investigated by Raman, infrared and photoluminescence spectroscopy. The samples were analysed immediately after the etching and six months later, while being stored in ambient air. The Raman spectra showed the shift in positions of transversal optical (TO) phonon bands, between freshly etched samples and the one stored in ambient air. Infrared spectra indicated the presence of SiH x species in the freshly etched samples, and appearance of oxidation after prolonged storage. Photoluminescence spectra were very weak in freshly etched samples, but their intensity has increased substantially in six month period. (doi: 10.5562/cca1971)

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“…19 But when the porosity is in the range of 55-75%, the lattice constant of the PS is 1-3% larger than that of the bulk silicon. 20,21 When the PS layer has the lattice mismatch with silicon substrate, a high residual stress (lateral and/or vertical stresses, depending on the applied current density and HF concentration) is expected to exist on their interface, which may cause the crack of the PS layer. 19,20 Therefore, the PS sample formed at 100 mA/cm 2 is susceptible to both lateral and vertical stresses, resulting from a larger lattice mismatch at PS-Si interface, which is expected to alter Raman and PL peak positions of PS samples, as will be discussed in the following sections.…”

Section: Resultsmentioning

confidence: 99%

Influence of applied current density on the nanostructural and light emitting properties of n-type porous silicon

Çetinel

Artunç

Şahin

et al. 2015

Int. J. Mod. Phys. B

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Effects of current density on nanostructure and light emitting properties of porous silicon (PS) samples were investigated by field emission scanning electron microscope (FE-SEM), gravimetric method, Raman and photoluminescence (PL) spectroscopy. FE-SEM images have shown that below 60 mA/cm 2 , macropore and mesopore arrays, exhibiting rough morphology, are formed together, whose pore diameter, pore depth and porosity are about 265-760 nm, 58-63 µm and 44-61%, respectively. However, PS samples prepared above 60 mA/cm 2 display smooth and straight macropore arrays, with pore diameter ranging from 900-1250 nm, porosity of 61-80% and pore depth between 63-69 µm. Raman analyses have shown that when the current density is increased from 10 mA/cm 2 to 100 mA/cm 2 , Raman peaks of PS samples shift to lower wavenumbers by comparison to crystalline silicon (c-Si). The highest Raman peak shift is found to be 3.2 cm −1 for PS sample, prepared at 90 mA/cm 2 , which has the smallest nanocrystallite size, about 5.2 nm. This sample also shows a pronounced PL, with the highest blue shifting, of about 12 nm. Nanocrystalline silicon, with the smallest nanocrystallite size, confirmed by our Raman analyses using microcrystal model (MCM), should be responsible for both the highest Raman peak shift and PL blue shift due to quantum confinement effect (QCE).

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Lattice-mismatch induced-stress in porous silicon films

Cited by 56 publications

References 13 publications

Direct characterization of nanocrystal size distribution using Raman spectroscopy

Direct characterization of nanocrystal size distribution using Raman spectroscopy

Micro and Nano Structure of Electrochemically Etched Silicon Epitaxial Wafers

Influence of applied current density on the nanostructural and light emitting properties of n-type porous silicon

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