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.

Structure and optical properties of Nb2O5 sculptured thin films by glancing angle deposition

“…The actual film thickness is different with substrate tilted angle. Theoretically, the vapor flux arriving at the substrate is proportional to the cosine of the tilted angle [14]. While the atomic shadowing increases with substrate tilted and crease increasing porosity in the film, the actual film thickness measured by SEM is larger than that predicted by the cosine trend.…”

“…STF with highly oriented columnar structure will result in optical anisotropy. When transmission spectra were measured with two orthogonal directions of incident polarized light, in-plane birefringence (Dn) was defined as the difference (n s À n p ) between the two in-plane refractive indices [14]. Fig.…”

Developing 1D nanostructure arrays for future nanophotonics

“…These techniques have been demonstrated to allow fabrication of single-material optical interference coatings [35], broadband antireflection coatings [36], and other photonic crystals [37,38]. While fractal scaling effects have been found to limit the utility of these films for some applications [39,40], these atomic-scale architectures appear to be uniquely functional three-dimensional (3-D) organized materials [41][42][43][44].…”

Ellipsometric Characterization on Multi-Layered Thin Film Systems during Hydrogenation

“…10,11) In order to make full use of ellipsometric data, theoretical modeling has been developed for measurement of thin film thickness and refractive index 12) and for quantitative description of optical and electric properties. 13) Without rationally designed modeling, accurate properties cannot be estimated in practice.…”