Structural Determination of Nanocrystalline Si Films Using Ellipsometry and Raman Spectroscopy

TL;DR

This study combines spectroscopic ellipsometry and Raman spectroscopy to analyze the microstructural evolution of nanocrystalline silicon films during growth, revealing insights into crystallite sizes, morphology, and effects of H2 dilution.

Contribution

It introduces a bimodal size distribution analysis in Raman data for more accurate microstructural characterization of nanocrystalline silicon films.

Findings

Identification of two distinct crystallite size populations during film growth

H2 dilution influences microstructure and morphology of silicon films

Spectroscopic techniques effectively elucidate microstructural evolution

Abstract

Single phase nano and micro crystalline silicon films deposited using SiF4/H2 plasma at different H2 dilution levels were studied at initial and terminal stages of film growth with spectroscopic ellipsometry (SE), Raman scattering (RS) and atomic force microscopy (AFM). The analysis of data obtained from SE elucidates the microstructural evolution with film growth in terms of the changes in crystallite sizes and their volume fractions, crystallite conglomeration and film morphology. The effect of H2 dilution on film microstructure and morphology, and the corroborative findings from AFM studies are discussed. Our SE results evince two distinct mean sizes of crystallites in the material after a certain stage of film growth. The analysis of Raman scattering data for such films has been done using a bimodal size distribution of crystallite grains, which yields more accurate and physically rational microstructural picture of the material.