Influence of substrate absorption on the optical and geometrical characterization of thin dielectric films
- 1 December 2002
- journal article
- Published by Optica Publishing Group in Applied Optics
- Vol. 41 (34), 7300-7308
- https://doi.org/10.1364/ao.41.007300
Abstract
The role played by a glass substrate on the accurate determination of the optical constants and the thickness of a thin dielectric film deposited on it, when well-known envelope methods are used, is discussed. Analytical expressions for the two envelopes of the optical transmission spectra corresponding to films with both uniform and nonuniform thicknesses are derived, assuming the substrate to be a weakly absorbing layer. It is shown that accurate determination of the refractive index and the film thickness is notably improved when the absorption of the substrate is considered. The analytical expressions for the upper and lower envelopes are used to characterize optically and geometrically both uniform and nonuniform amorphous chalcogenide films. The results obtained are compared with those derived by use of expressions for the envelopes that neglect the substrate absorption. The comparison shows that overestimated refractive indexes and underestimated thicknesses are obtained when the conventional approach, in which the substrate absorption is neglected, is used.Keywords
This publication has 16 references indexed in Scilit:
- Method for determining the optical constants of thin dielectric films with variable thickness using only their shrunk reflection spectraJournal of Physics D: Applied Physics, 2001
- Method of the ratio of envelopes of the reflection spectrum for measuring optical constants and thickness of thin filmsOptics and Spectroscopy, 2000
- Determination of the optical constants and thickness of thin films on slightly absorbing substratesApplied Optics, 1995
- Optical-constant calculation over an extended spectral region: application to titanium dioxide filmApplied Optics, 1995
- Optical characterization of wedge-shaped thin films of amorphous arsenic trisulphide based only on their shrunk transmission spectraThin Solid Films, 1995
- Flow-graph approach for optical analysis of planar structuresApplied Optics, 1994
- Calculation of the optical constants of a thin layer upon a transparent substrate from the reflection spectrumJournal of Physics D: Applied Physics, 1989
- Determination of surface roughness and optical constants of inhomogeneous amorphous silicon filmsJournal of Physics E: Scientific Instruments, 1984
- Determination of the thickness and optical constants of amorphous siliconJournal of Physics E: Scientific Instruments, 1983
- A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin filmJournal of Physics E: Scientific Instruments, 1976