Abstract: Absorption properties of an optically active medium can be changed drastically by a Fabry-Perot microcavity. Optically active medium of the cavity includes a host material which is not optically active and at least one rare earth ion which provides optical activity to the medium. The Fabry-Perot cavity is designed to be resonant with excitation wavelength of an absorption band of the host material. The excitation is provided by a source of radiation positioned such that the radiation impinges on the cavity at an angle within a range of from zero to less than 90 degrees from the normal to the top surface of the cavity. In one embodiment Er-implanted SiO.sub.2 is used as the optically active medium. SiO.sub.2 :Er has an absorption band at 980 nm and an emission band at 1.55 .mu.m due to 4f intra-atomic transitions of Er.sup.3+ ions. The Fabry-Perot cavity is designed to be resonant with the 980 nm absorption band of SiO.sub.2 :Er.

Abstract: This invention embodies an optical device with a Fabry-Perot cavity formed by two reflective mirrors and an active layer which is doped with a rare earth element selected from lanthanide series elements with number 57 through 71. The thickness of the active layer being a whole number multiple of .lambda./2 wherein .lambda. is the operating, or emissive, wavelength of the device, said whole number being one of the numbers ranging from 1 to 5, the fundamental mode of the cavity being in resonance with the emission wavelength of said selected rare earth element. Cavity-quality factors exceeding Q=300 and finesses of 73 are achieved with structures consisting of two Si/SiO.sub.2 distributed Bragg reflector (DBR) mirrors and an Er-implanted (.lambda./2) SiO.sub.2 active region. The bottom DBR mirror consists of four pairs and the upper DBR mirror consists of two-and-a half pairs of quarterwave (.lambda./4) layers of Si and SiO.sub.2.

Abstract: It has been discovered that co-doping of Er-doped Si with a light element such as C, N or F can result in substantially increased Er luminescence. A further increase in luminescence can result if, in addition, oxygen is present in the Si. Apparatus or systems according to the invention comprise a device (e.g., laser, optical ampifier, LED) that comprises a planar waveguide whose core region contains, in addition to at least 90 atomic % Si or SiGe alloy, Er, Pr and/or Nd, and further contains C, N and/or F, and preferably also contains oxygen. Currently preferred apparatus or systems according to the invention comprise means for electrically pumping the waveguide means.

Abstract: Disclosed is apparatus comprising an optically pumped optical gain device that comprises a rare earth (RE)-doped planar waveguide with non-uniform dopant distribution in the core of the waveguide. The RE ions are advantageously distributed such that the ions are concentrated in a core region in which the mode intensity of both signal radiation and pump radiation is relatively high. In preferred embodiments of a single mode planar waveguide according to the invention the RE ions are substantially concentrated in the central core region. A method of making the disclosed apparatus is also disclosed. The method involves implantation of RE ions into the core region.

Abstract: A method for forming heterostructures comprising multiconstituent epitaxial material, on a substrate comprises formation of a layer of "precursor" material on the substrate, and momentarily melting the precursor material by pulsed irradiation. The precursor material has the same major chemical constituents as the multiconstituent material to be formed, albeit not necessarily in the same proportions. In at least some systems (e.g., nickel or cobalt silicides on Si), solid state annealing of the re-solidified material often improves substantially the quality of the epitaxial material formed, resulting in substantially defect-free, substantially monocrystalline, material. An exemplary application of the inventive method is the formation of single crystal epitaxial NiSi.sub.2 on Si(100).

Abstract: Described is a method for producing semiconductor heterostructures incorporating a metal layer. The metal layer, typically a metal-silicide, can be produced by, e.g., co-deposition or reaction with the substrate. The resulting silicide is typically epitaxial and of high crystalline perfection.

Abstract: A very thin gold coating (e.g., 270 to 3,500 Angstroms) is vapor deposited on the surface of a nickel substrate. A short radiant energy pulse from a laser having a pulse length of about 130 nanoseconds is directed at the coated surface to melt portions of the gold coating and the nickel substrate therebelow. The energy pulse is removed to permit the melted material to resolidify as an alloy with a high concentration of gold at the surface thereof.

Abstract: Described are semiconductor heterostructures incorporating a metal layer. Devices based on the heterostructures are described, as are techniques for preparing the heterostructures. Specific embodiments wherein the metal layer is a metal silicide are detailed, and hot electron devices using this structure are analyzed briefly.

Abstract: The method for growing heteroepitaxial multiconstituent material on a substrate comprises deposition of a thin disordered layer of a "template-forming" material, i.e., material containing at least one constituent of the multiconstituent material to be grown, and differing in chemical composition from at least the substrate material, on the substrate surface at a relatively low deposition temperature, raising the substrate temperature to an intermediate transformation temperature, thereby causing the template-forming material to undergo a reaction that results in formation of "template" material, typically material having substantially the same composition as the multiconstituent material to be grown. Onto the thus formed template layer is then deposited the material for the epitaxial multiconstituent layer. This general process is exemplified by the growth of NiSi.sub.2 on a Si substrate, by first depositing at room temperature about 18.ANG.

Abstract: A technique isdescribed for removing defects and disorder from crystalline layers and the epitaxial regrowth of such layers. The technique involves depositing short term bursts of energy over a limited spatial region of a material thereby annealing the otherwise damaged material and causing it to epitaxially regrow. Subsequent to the short term energy deposition, similar processing is sequentially effected on adjoining and overlapping regions such that a pattern is ultimately "written". This pattern forms a continuous region of essentially single crystal material.