Accession Number:

ADA058382

Title:

Infrared Absorption in Zinc Selenide Thin Films.

Descriptive Note:

Final rept. 1 Jul 74-30 Jun 77,

Corporate Author:

AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OHIO

Personal Author(s):

Report Date:

1978-05-01

Pagination or Media Count:

92.0

Abstract:

Low loss antireflection coatings for infrared laser windows have been found to have absorption coefficients which are three to four orders of magnitude higher than was predicted from bulk material properties. An investigation of the causes for this increase in zinc selenide coatings was performed. Prior growth studies and theoretical descriptions of the thin film growth process indicated that variations in stoichiometry might be a cause for the high absorption measured in the coatings. An experimental program in which zinc selenide coatings were deposited onto calcium fluoride substrates under a wide variety of conditions revealed that the infrared absorption of the coatings decreased as the deposition rate was lowered. This correlated directly with the theoretical predictions based upon stoichiometry variations. Several surface and chemical techniques indicated that the most probable cause for the abnormal absorption in zinc selenide thin films was an increase in the zinc to selenium ratio which could be controlled to some extent by proper selection of vacuum deposition conditions. Author

Subject Categories:

  • Lasers and Masers
  • Coatings, Colorants and Finishes

Distribution Statement:

APPROVED FOR PUBLIC RELEASE