Direct characterization of nanocrystal size distribution using Raman spectroscopy

Abstract

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.

Effect of the crystal size on the infrared and Raman spectra of bio hydroxyapatite of human, bovine, and porcine bones

“…[7,8] The phonon confinement model has been proposed to explain Raman spectra in nanosized systems because the surface states must be considered. [9][10][11][12] According to Gao et al, [13] the underlying mechanism behind the size-dependent Raman shifts is still quite controversial and an open problem. They proposed a theoretical method to explain the quantum confinement effects on the Raman spectra of semiconductor nanocrystals indicating that their shift is originated by two overlapping effects: the quantum effect shift and the surface effect shift.…”

Gas‐Phase Plasma Synthesis of Free‐Standing Silicon Nanoparticles for Future Energy Applications

“…For the surface chemistry analysis, Fourier transform infrared spectroscopy (FTIR) is commonly used. In a series of recent publications, we have demonstrated that Raman spectroscopy can be used as a standard diagnostic tool for the analysis of the size distribution and surface chemistry of Si‐NPs. Especially on size distribution analysis, we have shown that, Raman spectroscopy is non‐destructive and time‐efficient, and gives reliable results as the analyses agree well with other size analysis techniques like TEM and PL.…”

“…Si‐NP sizes were determined by the residence time distributions in the downstream plasma, which leads to a bimodal Si‐NP size distribution as a result of a rapidly expanding central beam (residence times of less than 10 ms), and surrounding background recirculation cells (residence times of 0.1–0.4 s), see Figure . Si‐NPs synthesized in the central beam are in the range 2–10 nm, and those that are synthesized in the recirculation cells are in the range 50–120 nm (Figures and ).…”

Size control, quantum confinement, and oxidation kinetics of silicon nanocrystals synthesized at a high rate by expanding thermal plasma

“…21,22,25 The morphology of Si NCs is characterized by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM), and the images with different magnifications were shown in Figs. 1(a)-1(c).…”

“…[18][19][20] Pioneering work was done for the deposition of Si NCs as well. 21,22 However, some key fundamental growth mechanisms and properties of Si NCs processed by ETP-CVD have not been explored yet, such as the oxidation kinetics and the size-dependent photoluminescence (PL) mechanism of the Si NCs. In this letter, we further explore the growth mechanisms of ETP-CVD to synthesize Si NCs under various deposition conditions, deposit free-standing Si NCs with a well-controlled size distribution for any specific application, and investigate the quantum confinement effects dependent on the size of Si NCs 23,24 and the oxidation kinetics at the surfaces of Si NCs.…”