Abstract

Aluminum oxide films have been deposited by ion-assisted deposition. The films were electron beam evaporated at a chamber temperature of 100°C with argon and/or oxygen ion bombardment. The optical constants of these films have been measured in the visible and UV: the refractive index of the films has been increased by the bombardment (to 1.70 at 350 nm), while the extinction coefficients are essentially unchanged (2 × 10⁻⁴ at 350 nm). Infrared transmittance measurements in the 3-μm water band show that even an unbombarded Al₂O₃ film with low refractive index (1.61 at 350 nm) contains virtually no water, indicating a very high packing density. We confirmed this result by observing no air-to-vacuum shift for the same film in a specially equipped spectrophotometer. All the Al₂O₃ films deposited in this experiment clearly approach unity packing density whether bombarded or not.

© 1987 Optical Society of America