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.
© 2004 Optical Society of America
(160.1190) Materials : Anisotropic optical materials
(260.1440) Physical optics : Birefringence
(260.2130) Physical optics : Ellipsometry and polarimetry
(310.1860) Thin films : Deposition and fabrication
(310.6860) Thin films : Thin films, optical properties
Gisia Beydaghyan, Kate Kaminska, Tim Brown, and Kevin Robbie, "Enhanced Birefringence in Vacuum Evaporated Silicon Thin Films," Appl. Opt. 43, 5343-5349 (2004)