Refractive index, dispersion, and birefringence of silicon carbide polytypes.
The refractive index of each of the four common silicon carbide polytypes has been measured over the visible range. The data were analyzed in an attempt to relate the birefringence to the relative hexagonal character of the polytype. A general relationship exists, namely, that the birefringence increases with increasing hexagonal character of the polytype. This relationship is not sufficiently precise to use for the identification of polytypes.
Broadband Antireflection and Light Extraction Enhancement in Fluorescent SiC with Nanodome Structures
We demonstrate a time-efficient and low-cost approach to fabricate Si3N4 coated nanodome structures in fluorescent SiC. Nanosphere lithography is used as the nanopatterning method and SiC nanodome structures with Si3N4 coating are formed via dry etching and thin film deposition process. By using this method, a significant broadband surface antireflection and a considerable omnidirectional luminescence enhancement are obtained. The experimental observations are then supported by numerical simulations. It is believed that our fabrication method will be well suitable for large-scale production in the future.
Electroluminescence in Disordered Zinc Sulphide
IN recent times a detailed study has been made of the structure of zinc sulphide crystals1, and of the solid-state properties, particularly electroluminescence2, of this compound. of the many factors which may influence the electrical and optical properties of zinc sulphide, little attention has so far been paid to the effect of the modifications which can occur in the crystal structure. In addition to the well-known cubic (sphalerite) and hexagonal (wurtzite) forms, single crystals of zinc sulphide can also be obtained with a one-dimensional stacking disorder of the hexagonal (0001) planes3. This disorder may exhibit a periodic arrangement resulting in the formation of polytypes1. Although no experimental work seems to have been published linking electroluminescence with disorder, Schneer4 has, from theoretical considerations, suggested that there may be some connexion; in addition, the electroluminescent properties of some zinc sulphide phosphors have been tentatively ascribed to a partial transformation from hexagonal to cubic5.