title: Enhanced birefringence in vacuum evaporated silicon thin films.
abstract: We report an experimental study of enhanced optical birefringence in silicon thin films on glass substrates. Form anisotropy is introduced as an atomic-scale morphological structure through dynamic control of growth geometry. The resulting birefringence is large compared with naturally anisotropic crystals and is comparable to two-dimensional photonic crystals. The films are fabricated with serial bideposition onto a substrate held at a fixed tilt angle relative to the impinging vapor. Films were analyzed by spectroscopic ellipsometry and scanning electron microscopy, the latter clearly revealing form anisotropy in a morphology of bunched columns perpendicular to the deposition plane with dimensions of hundreds of nanometers and smaller. The observed linear birefringence varies with wavelength and tilt angle, with a maximum of 0.4 at a 630-nm wavelength and 0.25 at 1500 nm.
authors.affiliation: Department of Physics, Queen's University, Kingston, Ontario K7L 3N6, Canada. gisia@physics.queensu.ca
authors.forename: Gisia
authors.initials: G
authors.lastname: Beydaghyan
authors.forename: Kate
authors.initials: K
authors.lastname: Kaminska
authors.forename: Tim
authors.initials: T
authors.lastname: Brown
authors.forename: Kevin
authors.initials: K
authors.lastname: Robbie