Raman spectroscopy of amorphous and microcrystalline silicon films deposited by low-pressure chemical vapor deposition

Abstract

In this work we used Raman spectroscopy to investigate the structural characteristics of as-deposited amorphous and micro-crystalline silicon films. For amorphous silicon films, the order (or disorder) of the silicon network was quantified using properties of the Raman spectra that were related to key deposition conditions. We found that a strong relationship exists between the structural order of the silicon matrix and the deposition temperature and deposition rate. A quantitative model was proposed relating the intensity ratio of transverse optical phonon peak to longitudinal optical phonon peak to the surface diffusion length, a parameter that was calculated from available data. It was found that optimization of the as-deposited silicon microstructure is possible by selecting deposition conditions yielding peak–ratio values in the vicinity of 0.53. For as-deposited micro-crystalline silicon films, Raman spectroscopy was used to estimate the initial crystalline fraction of the film and monitor the crystallization process during annealing. These data were used to confirm the crystallization mechanism in mixed-phase silicon films and identify the effect of different process parameters on the crystallization time of the annealed films.

Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

“…The broad shoulder near the nanocrystal Si peak of 513.5 cm −1 can be observed. As shown in Figure 1(b), we have deconvoluted the spectrum to obtain the peak centered at a wavenumber of 513.5 cm −1 which belongs to the nanocrystal Si, and four broad peaks which are the characteristic peaks of amorphous silicon at wavenumber of 480 cm −1 (transverse optical mode), 380 cm −1 (longitudinal optical mode), 301 cm −1 (longitudinal acoustic mode), and 150 cm −1 (transverse acoustic mode) [34][35][36][37][38][39]. The Raman spectrum analysis has revealed that nanostructured silicon and amorphous silicon were generated simultaneously during the laser irradiation.…”

Structural Characterization of SiF4, SiH4 and H2 Hot-Wire-Grown Microcrystalline Silicon Thin Films with Large Grains

“…The microcrystalline Raman spectra were fit to a sum of two Lorentzian peaks corresponding to the crystalline and amorphous phases. This allows us to calculate the crystalline volume fraction (x c ) from a ratio of the integrated peak intensities and average distance between point defects (l d ) from the full-width half maximum (FWHM) of the crystalline peak [13][14][15]. The apparatus used to gather the Raman spectra is composed of an Argon ion laser with a wavelength of 514.5 nm with a power of 300 mW, collection optics, 0.6 m triple monochromator, and a cooled CCD camera.…”

Single crystalline and core–shell indium-catalyzed germanium nanowires—a systematic thermal CVD growth study

“…The crystalline fraction F c in a material has sometimes been estimated by integrating the peak intensity associated with the amorphous and crystalline phases, I a and I c respectively [27]:…”