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Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Vol. 30, Iss. 7 — Mar. 1, 1991
  • pp: 839–846

Two-step regression procedure for the optical characterization of thin films

S. V. Babu, Moses David, and Ramesh C. Patel  »View Author Affiliations


Applied Optics, Vol. 30, Issue 7, pp. 839-846 (1991)
http://dx.doi.org/10.1364/AO.30.000839


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Abstract

A diode array rapid scan spectrometer is used for measuring the intensity of polychromatic light in the 300–420-nm range reflected from a diamondlike carbon film as a function of wavelength. With a fixed grating setting, the wavelength range of 120 nm can be covered in 23 ms. From the reflected intensity, a new two-step regression procedure is utilized to determine refractive index, bandgap, slope of the absorption edge, and film thickness. The calculated parameters are independent of the starting set and the sequence of parameter estimation. The accuracy of the regression procedure is verified by comparison to the envelope method. It is shown using simulated data that, for strongly absorbing films, the new regression procedure is more accurate than the envelope method. The new regression method can handle very noisy reflectance spectra also.

© 1991 Optical Society of America

History
Original Manuscript: January 5, 1990
Published: March 1, 1991

Citation
S. V. Babu, Moses David, and Ramesh C. Patel, "Two-step regression procedure for the optical characterization of thin films," Appl. Opt. 30, 839-846 (1991)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-30-7-839


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