Microstructure and optical properties of free-standing porous silicon films: Size dependence of absorption spectra in Si nanometer-sized crystallites

Kanemitsu, Yoshihiko; Uto, Hiroshi; Masumoto, Yasuaki; Matsumoto, Takahiro; Futagi, Toshiro; Mimura, Hidenori

doi:10.1103/physrevb.48.2827

Cited by 458 publications

(214 citation statements)

References 24 publications

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“…5,11 For Si nanocrystals in the few-nanometers range observations of broad bands in the visible region are frequently reported. A pure quantum confinement model predicts that for small enough crystallites radiative recombinations due to the excitonic transitions should appear in the visible region.…”

Section: B Photoluminescencementioning

confidence: 99%

“…Due to the restricted volume, the CB minima in perpendicular directions are shifted up more than the CB minima in longitudinal directions. There is a number of publications which derive expressions for enlargement of the energy band gap 11,23 with diminishing grain size. The enlargement consists of a downshift of the VB and an upshift of the CB.…”

Section: A Electron Paramagnetic Resonancementioning

confidence: 99%

“…This is a clear advantage when compared to other less discriminative techniques as used in the present and in earlier studies. 11,12 ͑2͒ Valence band. The effect of spatial confinement has been observed on a photoluminescence line at E Ϸ820 meV corresponding to a deep to shallow level transition.…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of band structure modification in silicon nanocrystals

et al. 2001

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Experimental studies of size-related effects in silicon nanocrystals are reported. We present investigations carried out on nanocrystals prepared from single-crystal Si:P wafer by ball milling. The average final grain dimension varied depending on the way of preparation in the range between 70 and 230 nm. The ball milling was followed by sedimentation and selection of the smallest grains. The initial grain size distribution was measured by scanning electron microscopy. Further reduction in size was achieved by oxidation at 1000°C which creates a silicon dioxide layer around a silicon core. The oxidation process was monitored by transmission electron microscopy and the growth speed of SiO 2 was estimated in order to model the grain size of nanocrystals. Crystallinity of silicon grains was confirmed by x-ray diffraction and by transmission electron microscopy using a bright/dark field method and selected area diffraction pattern. In the silicon nanocrystals the electron energy levels are shifted which was observed separately for conduction band, valence band and energy band gap. Electron paramagnetic resonance was applied to investigate variation of the conduction band minimum by monitoring its influence on the hyperfine interaction of phosphorus shallow donor. On the basis of these results an explicit expression for conduction band upshift as a function of average grain size has been derived. Information about the downshift of the valence band was obtained from measurements on a photoluminescence band related to a deep to shallow level transition. A perturbation of a few meV for grain sizes of the order about 100 nm has been observed. Internal consistency of these findings has been examined by investigation of the photoluminescence band due to an electron-hole recombination whose energy is directly related to the band gap of silicon.

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Section: B Photoluminescencementioning

confidence: 99%

Section: A Electron Paramagnetic Resonancementioning

confidence: 99%

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Experimental investigation of band structure modification in silicon nanocrystals

et al. 2001

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“…An explanation of the temperature dependence of the luminescence of porous silicon based on a similar mechanism has also been provided; the steady-state intensity-temperature data can be fitted by an equation based on the competition between a phonon-mediated radiative decay that shows normal Arrhenius temperature dependence and ionization of the excited state through a tunneling process at finite temperature which has a Berthelot-type temperature dependence, [44,60]. This model was successfully fitted to experimental data for the temperature dependence of luminescence from porous silicon [61,62]. The experimental data generally shows a maximum as a function of temperature that varies between $50 and 150 K in different samples [46,[61][62][63].…”

Section: Origin Of the Orange And Blue Pl Emissionmentioning

confidence: 99%

“…This model was successfully fitted to experimental data for the temperature dependence of luminescence from porous silicon [61,62]. The experimental data generally shows a maximum as a function of temperature that varies between $50 and 150 K in different samples [46,[61][62][63].…”

Section: Origin Of the Orange And Blue Pl Emissionmentioning

confidence: 99%