Ion-assisted deposition of optical thin films. Doctoral thesis

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6693140

Targove, J D

The columnar microstructure of most thermally evaporated thin films detrimentally affects many of their properties through a reduction in packing density. In this work, the author investigated ion-assisted deposition as a means of disrupting this columnar growth for a number of coating materials. A Kaufman hot-cathode ion source bombarded thermally evaporated films with low-energy (<1000 eV) positive ions during deposition in a cryopumped box coater. The author investigated MgF/sub 2/, Na/sub 3/AlF/sub 6/, AlF/sub 3/, LaF/sub 3/,CeF/sub 3/,NdF/sub 3/,Al/sub 2/O/sub 3/, and AlN. Argon ion bombardment of the fluoride coatings increased their packing densities dramatically. He achieved packing densities near unity without significant absorption for MgF/sub 2/,LaF/sub 3/, and NdF/sub 3/, while Na/sub 3/AlF/sub 6/,AlF/sub 3/, and CeF/sub 3/ began to absorb before unity packing density could be achieved. Fluorine was preferentially sputtered by the ion bombardment, creating anion vacancies. The films adsorbed water vapor and hydroxyl radicals from the residual chamber atmosphere. These filled the vacancy sites, eliminating absorption in the visible, but the oxygen complexes caused increased absorption in the ultraviolet. For LaF/sub 3/ and NdF/sub 3/, a sufficient amount of oxygen caused a phase transformation from the fluoride phase to an oxyfluoride phase.

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA)
• OSTI ID: 6693140
• Report Number(s): AD-A-196876/7/XAB; AFIT/CI/NR-88-57
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure &amp; Phase Studies
ABSORPTION
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
ANIONS
ARGON
ATMOSPHERES
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
COATINGS
CRYSTAL STRUCTURE
DEPOSITION
ELEMENTS
FILMS
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GASES
HALIDES
HALOGEN COMPOUNDS
HYDROXYL RADICALS
IONS
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PNICTIDES
RADICALS
RARE GASES
SORPTION
SPUTTERING
THIN FILMS
VAPORS
WATER VAPOR