Abstract: A protective mask and a method of localized anodic thinning to prevent exsive thinning of an epitaxial layer in the forming of a field effect transistor. A moat exposing the epitaxial layer is provided in the protective mask surrounding a device pattern or group of patterns to be formed in the epitaxial layer by anodic thinning. During the thinning process, the area of the epitaxial layer exposed by the moat becomes fully depleted and cuts off current into the region surrounded by the moat and prevents excessive thinning of the epitaxial layer under the design pattern.

Abstract: This disclosure concerns optical waveguides of semiconductor material through which light is adapted to be propagated. The optical waveguides comprise respective first and second layers of semiconductor material of the same conductivity type, wherein one of the semiconductor layers has a relatively low refractive index, while the other semiconductor layer has a relatively high refractive index, with the light being adapted to be propagated through the semiconductor layer having the relatively high refractive index. The optical waveguide structures are characterized by having the semiconductor layer through which the light is to be propagated so formed as to include each of its two side surfaces and top surface as being planar faceted growth surfaces of extreme smoothness to avoid scattering light as it is being propagated therethrough, thereby minimizing losses.

Abstract: This disclosure concerns optical waveguides of semiconductor material through which light is adapted to be propagated. The optical waveguides comprise respective first and second layers of semiconductor material of the same conductivity type, wherein one of the semiconductor layers has a relatively low refractive index, while the other semiconductor layer has a relatively high refractive index, with the light being adapted to be propagated through the semiconductor layer having the relatively high refractive index. The optical waveguide structures are characterized by having the semiconductor layer through which the light is to be propagated so formed as to include each of its two side surfaces and top surface as being planar faceted growth surfaces of extreme smoothness to avoid scattering light as it is being propagated therethrough, thereby minimizing losses.