Study on the applied limitation of the micro‐crystal model for Raman spectra of nano‐crystalline semiconductors

Abstract

The limitation in sample size and the choice in parameters for the application of the micro-crystal (MC) model have been tested and discussed. The testing was performed through the fitting of calculated Raman spectra by using the MC model with the observed Raman spectra for nearly uniform-sized nanocrystalline (NC)-Si of smaller than 2 nm. The results showed that the good fittings could not be obtained, if the phonon dispersion curves !.q/ and Raman linewidths 0 of bulk-crystals (BCs) were used, i.e. if the bulk-like approximation (BLA) was used in the fitting. Moreover, an analysis of the fitting results indicates that when the size of NC-Si is smaller than about 4 nm, the MC model based on -BLA will be invalid.

Interlayer vibrational modes in few-quintuple-layerBi2Te3andBi2Se3two-dimensional crystals: Raman spectroscopy an

“…6(d) and 6(e). The broadening of the A 1 1g and A 2 1g peaks with decreasing thickness follows the phenomenological exponential relationship 0 (d) = A + B exp(−d/C), where d represents the thickness of the Bi 2 Te 3 nanoplates, and A, B, and C are fitting parameters [15,42]. Good fitting was achieved with A = 2.4 ± 0.08, B = 33.9 ± 7.9, and C = 1.1 ± 0.1 for A 1 1g and A = 7.6 ± 0.03, B = 46.0 ± 7.4, and C = 0.9 ± 0.05 for A 2 1g , as shown by the blue solid lines in Fig.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part III

“…Raman spectra of nanocrystal semiconductors usually exhibit new features that are different from those of the corresponding bulk-crystalline semiconductors. A study on the limitation of a micro-crystal model for describing Raman spectra of such nanocrystalline semiconductors was reported by Zhang et al [202] Thermo-Raman spectroscopy was used by Zhao et al [203] to study the transition of micro-sized α-GaO(OH) to β-Ga 2 O 3 rods. Observed vibrational bands were assigned.…”

A Review of Chinese Raman Spectroscopy Research Over the Past Twenty Years

“…From the fitting, it was found that the MC model is invalid for Si crystallites smaller than ∼4 nm with nearly uniform size if the dispersion curve ω( q ) and linewidth г( q ) are chosen based on the bulk-like approximation (BLA), and the characteristics of the dispersion curve and Raman linewidth appearing in the best fit are different from those predicted by the BLA. 6…”

“…From the fitting, it is found that the MC model is invalid for Si crystallites smaller than ∼4 nm with nearly uniform size if the dispersion curve ω( q ) and linewidth r ( q ) are chosen based on the BLA, and the characteristics of the dispersion curve and Raman linewidth appearing in the best fit are different from those predicted by the BLA. 114 In recent years, they have mainly carried out research upon the Raman spectra of nanostructured semiconductors and carbon nanotubes, as well as the MP Raman spectra of ZnO nanoparticles. The reliability of the optical model Raman frequency with size-independent phenomena of single-phonon and MP in polar semiconductors such as ZnO was demonstrated.…”