Inelastic light scattering by longitudinal acoustic phonons in thin silicon layers: From membranes to silicon-on-insulator structures

J. Groenen, F. Poinsotte, A. Zwick, C. M. Sotomayor Torres, Mika Prunnila, Jouni Ahopelto

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    We report on inelastic light scattering (ILS) by longitudinal acoustic phonons in thin Si(001) layers (thickness ≈ 30 nm). Calculations based on the photoelastic model are presented for unsupported and supported layers. We consider ILS by standing longitudinal acoustic modes along [001]. Our calculations take into account the spatial modulations of acoustic, optical, and photoelastic properties. We successively identify their contributions to the scattering efficiency and find that there is a strong interplay between acoustic, optical, and photoelastic cavity effects. The need to consider optical cavity effects is pointed out. It is shown here that they can be included in a convenient way in the scattered electromagnetic fields, by solving the wave equation in the presence of the polarization induced by the photoelastic effect. A detailed analysis of the scattering efficiency (peak frequencies, intensities, and widths) is presented. The dependence of the ILS spectra on film thickness and on substrate characteristics are addressed. Calculations are successfully compared to experimental data for thin Si membranes and silicon-on-insulator structures. It is shown that the inelastic light scattering involves a set of discrete quantized acoustic modes for membranes and a continuum of acoustic modes for silicon-on-insulator structures.
    Original languageEnglish
    Article number045420
    Number of pages12
    JournalPhysical Review B: Condensed Matter and Materials Physics
    Issue number4
    Publication statusPublished - 2008
    MoE publication typeA1 Journal article-refereed



    • elemental semiconductors
    • light scattering
    • membranes
    • phonons
    • photoelasticity
    • Raman spectra
    • semiconductor thin films
    • thin films
    • silicon
    • silicon-on-insulator
    • SOI

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