Abstract: The specification describes a process and apparatus for collapsing preform tubes in Modified Chemical Vapor Deposition processes. The problem of bubble formation during tube collapse was found to be attributable to excess dopant vapor pressure emitted from the hot zone during the final stage of tube collapse. This excess pressure is controlled by cooling the tube in advance of the torch, thereby decreasing the viscosity of the dopant vapor and increasing its transport rate. This is found to reduce internal tube pressure and eliminate bubble formation in the collapsed preform.

Abstract: A VCSEL comprises separate current and optical guides that provide unique forms of drive current and transverse mode confinement, respectively. In one embodiment, the optical guide comprises an intracavity high refractive index mesa disposed transverse to the cavity resonator axis and a multi-layered dielectric (i.e., non-epitaxial) mirror overlaying the mesa. In another embodiment, the current guide comprises an annular first electrode which laterally surrounds the mesa but has an inside diameter which is greater than that of an ion-implantation-defined current aperture. The current guide causes current to flow laterally from the first electrode along a first path segment which is essentially perpendicular to the resonator axis, then vertically from the first segment along a second path segment essentially parallel to that axis, and finally through the current aperture and the active region to a second electrode.

Abstract: The invention is an apparatus and method for cleaving a semiconductor bar and coating the cleaved facets within a vacuum environment. The apparatus is a fixture having at least one rotator for cleaving one or more semiconductor samples into semiconductor bars and positioning the semiconductor bars for immediate coating of their cleaved facets. The fixture is operably positioned within a processing chamber and exposed to a conventional coating medium before, during or immediately after cleaving the semiconductor sample. The fixture cleaves the semiconductor samples in a manner that reduces semiconductor sample waste and also allows the processing environment requirements to be reduced compared to other cleaving and coating techniques. A single actuation feed-through mechanism actuates the fixture from outside of the processing chamber.