Effects of sputtering through small apertures on the refractive index of niobium pentoxide films

Journal Article · Sun May 01 04:00:00 EDT 1988 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.575284· OSTI ID:5220912

Hickernell, F S

Niobium pentoxide (Nb/sub 2/O/sub 5/) can be reactively rf sputtered to produce high-index low-loss amorphous films for use as integrated optical (IO) components. Tight tolerances are required on refractive index, loss, scatter, and geometric form. Of particular interest to IO devices are thin-film Luneburg lenses which have been successfully employed on lithium niobate (LiNbO/sub 3/) based acousto-optic spectrum analyzers. To develop a particular lens configuration it is necessary to sputter through a circular aperture mask in contact with the LiNbO/sub 3/. Experimental evidence has shown that there is a significant drop in refractive index under fixed deposition conditions as the ratio of aperture diameter to mask thickness A/t is decreased. For an A/t ratio of 7.0 the index is 2.272 while an A/t ratio of 1.0 results in an index of 2.224. Increasing the power to the Nb target and bias sputtering have been successfully applied to raise the index. An increase in power from 70 to 400 W raised lens indices from 2.220 to 2.280. Bias sputtering similarly increases lens indices but distorted the lens profile. The mechanisms influencing refractive index change in amorphous Nb/sub 2/O/sub 5/ films sputtered under varying deposition conditions are discussed.

• Research Organization: Motorola Inc., Government Electronics Group, Scottsdale, Arizona 85252
• OSTI ID: 5220912
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 6:3; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALI METAL COMPOUNDS
CHALCOGENIDES
COATINGS
DEPOSITION
LENSES
LITHIUM COMPOUNDS
NIOBATES
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REFRACTIVITY
REFRACTORY METAL COMPOUNDS
SCATTERING
SPUTTERING
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS