Determining thin film properties by fitting optical transmittance

Journal Article · Wed Aug 15 04:00:00 EDT 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.346617· OSTI ID:6766686

Klein, J D; Yen, A; Cogan, S F ^[1]

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1. EIC Laboratories, Norwood, Massachusetts 02062 (USA)

The optical transmission spectra of rf sputtered tungsten oxide films on glass substrates were modeled to determine absorption edge behavior, film thickness, and index of refraction. Removal of substrate reflection and absorption phenomena from the experimental spectra allowed direct examination of thin film optical characteristics. The interference fringe pattern allows determination of the film thickness and the dependence of the real index of refraction on wavelength. Knowledge of the interference fringe behavior in the vicinity of the absorption edge was found essential to unambiguous determination of the optical band gap. In particular, the apparently random deviations commonly observed in the extrapolation of as-acquired data are eliminated by explicitly considering interference fringe phenomena. The multivariable optimization fitting scheme employed allows air-film-substrate reflection losses to be compensated without making reflectance measurements.

• DOE Contract Number: AC03-87SF16733
• OSTI ID: 6766686
• Journal Information: Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 68:4; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
CHALCOGENIDES
DIMENSIONS
FILMS
GLASS
INTERFERENCE
LIGHT TRANSMISSION
MATHEMATICAL MODELS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REFRACTIVITY
REFRACTORY METAL COMPOUNDS
SPECTRA
SPUTTERING
SUBSTRATES
THICKNESS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES