Abstract

Ion-assisted deposition (IAD) has been widely studied as a means of improving the properties of optical thin films.¹ Metal fluorides are a case in point, with MgF₂ in particular being studied by several groups. Oxygen is a major impurity in IAD fluoride films; however, the nature of the oxygen incorporation has remained unresolved. In order to gain insight into the IAD process with metal fluorides, we have extensively studied the IAD of LaF₃.² A major advantage of LaF₃ in this work is its highly crystalline nature, even when deposited onto ambient temperature substrates. Our results with LaF₃ have clarified the nature of the oxygen incorporation in fluoride films. Identical results have been observed with CeF₃ and NdF₃ thin films, which are also highly crystalline.³ While we have also studied MgF₂ and other low-index fluorides,³ the lack of x-ray diffraction peaks with these materials has prevented us from making similar direct observations; however, we expect the nature of the oxygen incorporation to be very similar for these materials.

© 1988 Optical Society of America