Structure and hydrogen content of polymorphous silicon thin films studied by spectroscopic ellipsometry and nuclear measurements

A. Fontcuberta i Morral, P. Roca i Cabarrocas, and C. Clerc
Phys. Rev. B 69, 125307 – Published 10 March 2004
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Abstract

The dielectric functions of amorphous and polymorphous silicon films prepared under various plasma conditions have been deduced from UV-visible spectroscopic ellipsometry measurements. The measured spectra have been first simulated by the use of the Tauc-Lorentz dispersion model and then the compositions of the films have been obtained by the use of the tetrahedron model combined with the Bruggeman effective medium approximation. This approach allows us to determine the hydrogen content, the crystalline fraction, and the void fraction of the films. This is particularly important in the case of polymorphous films in which the low crystalline fraction (below 10%) can only be detected when an accurate description of the effects of hydrogen on the dielectric function through the tetrahedron model is considered. The hydrogen content and film porosity deduced from the analysis of the spectroscopic ellipsometry measurements are in excellent agreement with the hydrogen content and film density deduced from combined elastic recoil detection analysis and Rutherford backscattering spectroscopy measurements. Moreover, despite their high hydrogen content (∼15%–20%) with respect to hydrogenated amorphous silicon films deposited at the same temperature (8%), polymorphous silicon films have a high density, which is related to their very low void fraction.

  • Received 24 July 2003

DOI:https://doi.org/10.1103/PhysRevB.69.125307

©2004 American Physical Society

Authors & Affiliations

A. Fontcuberta i Morral and P. Roca i Cabarrocas*

  • Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647 CNRS), Ecole Polytechnique, F-91128 Palaiseau Cedex, France

C. Clerc

  • CSNSM, Bâtiment 108, Université Paris Sud, 91405 Orsay Campus, France

  • *Author to whom correspondence should be addressed. Electronic address: roca@poly.polytechnique.fr

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Vol. 69, Iss. 12 — 15 March 2004

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