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Proceedings Paper

Infrared absorption in chemically vapor-deposited ZnSe: wavelength and temperature dispersions
Author(s): Claude A. Klein
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Paper Abstract

Chemically vapor-deposited ZnSe exhibits outstanding properties in the infrared (IR) and has been established as a prime material candidate for IR transmitting applications. The purpose of this paper is to present and evaluate data on both the surface and the bulk absorption of commercially available ZnSe, over the entire wavelength and temperature range of current interest. This investigation is based on spectral emittance measurements that were carried out by Stierwalt at the Naval Ocean Systems Center and on in-house transmission spectroscopy performed in the context of a fur-window development program. Surface effects can be felt at wavelengths as high as 14 um and usually predominate at wavelengths of less than 8 urn, even for fairly thick specimens. Fractional surface absorptions are temperature independent from about 200 to 400 K, which masks the behavior of the bulk absorption, and can be fitted to a Fourier series, for wavelengths of 3.5 to 13.5 urn. Bulk absorption coefficients (nv) are strongly dependent upon temperature as well as wavelength but can be approximated by means of two bivariate polynomial expressions that yield "recommended" values. At wavelengths X 10 urn, v always decreases with increasing temperature; it is shown that a wavelength independent Debye-Waller factor provides a correct description of the temperature dependence, thus pointing to IR-active localized modes. At wavelengths X 14 urn, V always increases with rising temperature and exhibits a temperature-dependence pattern as predicted for 3- and 4-phonon summation processes. Finally, an analysis of the temperature dependence of j at 10.6 urn demonstrates that the intrinsic lattice-vibrational contribution to bulk absorption at the CO2-laser wavelength should be close to 4x1Ocrn, in accord with the results of earlier lasercalorimetry tests performed on exceptionally pure ZnSe.

Paper Details

Date Published: 1 October 1990
PDF: 24 pages
Proc. SPIE 1307, Electro-Optical Materials for Switches, Coatings, Sensor Optics, and Detectors, (1 October 1990); doi: 10.1117/12.21698
Show Author Affiliations
Claude A. Klein, Raytheon Research Div. (United States)

Published in SPIE Proceedings Vol. 1307:
Electro-Optical Materials for Switches, Coatings, Sensor Optics, and Detectors
Rudolf Hartmann; M. J. Soileau; Vijay K. Varadan, Editor(s)

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