Accession Number : ADA196876


Title :   The Ion-Assisted Deposition of Optical Thin Films


Descriptive Note : Doctoral thesis


Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH


Personal Author(s) : Targove, James D


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a196876.pdf


Report Date : Jan 1988


Pagination or Media Count : 214


Abstract : The columnar microstructure of most thermally evaporated thin films detrimentally affects many of their properties through a reduction in packing density. In this work, we have 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. We have investigated MgF2, Na3AIF6, AIF3, LaF3,CeF3,NdF3,Al2O3, and AIN. Argon ion bombardment of the fluoride coatings increased their packing densities dramatically. We achieved packing densities near unity without significant absorption for MgF2,LaF3, and NdF3, while Na3AIF6,AIF3, and CeF3 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 LaF3 and NdF3, a sufficient amount of oxygen caused a phase transformation from the fluoride phase to an oxyfluoride phase. Theses. (mjm)


Descriptors :   *DEPOSITION , *FLUORIDES , *ION BOMBARDMENT , *OPTICAL MATERIALS , *THIN FILMS , ABSORPTION , ADSORPTION , ANIONS , ARGON , ATMOSPHERES , CATIONS , CHAMBERS , COATINGS , FLUORINE COMPOUNDS , GROWTH(GENERAL) , HYDROXYL RADICALS , IONS , MICROSTRUCTURE , OXYGEN , PACKING DENSITY , PHASE TRANSFORMATIONS , RESIDUALS , THESES , WATER VAPOR


Subject Categories : Inorganic Chemistry


Distribution Statement : APPROVED FOR PUBLIC RELEASE