Abstract: A class of superconductive materials containing copper-oxygen bonding and with mixed cation-occupancy designed with a view to size and valence consideration yield useful values of critical temperature and other properties. Uses entail all applications which involves superconducting materials such as magnets and transmission lines which require continuous superconductivity paths as well as detectors (e.g., which may rely on tunneling).

Abstract: A class of superconductive materials containing copper-oxygen bonding and with mixed cation-occupancy designed with a view to size and valence consideration yield useful values of critical temperature and other properties. Uses entail all applications which involves superconducting materials such as magnets and transmission lines which require continuous superconductivity paths as well as detectors (e.g., which may rely on tunneling).

Abstract: A class of superconductive materials containing copper-oxygen bonding and with mixed cation-occupancy designed with a view to size and valence consideration yield useful values of critical temperature and other properties. Uses entail all applications which involves superconducting materials such as magnets and transmission lines which require continuous superconductivity paths as well as detectors (e.g., which may rely on tunneling).

Abstract: Superconducting copper oxides of the perovskite structure are modified to have mixed occupancy of a cation site, thereby resulting in increased limits in critical field and/or critical current. Mixed occupancy may be observed in terms of increased resistivity as the superconducting material reverts to a nonsuperconducting state. A significant advantage, at least for preferred compositions, derives from the fact that critical temperature is unaffected relative to the prototypical material.

Abstract: A plurality of PR measurements are simultaneously made at N different spots on a wafer by forming N modulated pump beams and N tunable probe beams, and directing one pump beam and one probe beam so as to form overlapping images at each of the N spots. Each of a like plurality of N photodetectors receives a portion of the corresponding probe beam which is reflected from the surface of the wafer to provide information about the wafer characteristics at each spot. In one embodiment, automatic alignment of the probe and pump beams along a row of N spots is achieved by means of a semi-cylindrical scan head which has an axial cavity overlapping the row of N spots and a plurality of radial cavities organized into separate, but interleaved input and output groups. The cavities of two separate input groups receive optical fibers carrying the probe and pump beams to the row of N spots. The cavities of two separate output groups receive photodetectors for detecting the reflected beam and for monitoring the pump beam.

Abstract: A subassembly for coupling a laser to an optical fiber comprises a substrate having an asymmetrical, pyramidal cavity, a spherical lens located in the cavity, and a semiconductor laser positioned on the substrate. The output face of the laser is located along an edge of the cavity (without overhanging the edge), and its active region is aligned with the center of the lens along the optic axis of the subassembly.

Abstract: In a DH-PHEMT the channel layer comprises InGaAs and the donor layers comprise In.sub.0.5-q (Al.sub.x Ga.sub.1-x).sub.0.5+q P in which the mole fraction of Al is in the range of about 0.2.ltoreq.x.ltoreq.0.3. In another embodiment, an InAlGaP layer forms a Schottky barrier gate contact with a barrier height of about 1.0 eV and hence low leakage current. The devices exhibit high 2DEG density, current drivability, and breakdown voltage, making them suitable for low voltage application such as battery-powered, portable wireless equipment. The Schottky barrier contact may be used in devices other than HEMTs.

Abstract: This application discloses, to the best of our knowledge, the first unipolar laser. An exemplary embodiment of the laser was implemented in the GaInAs/AlInAs system and emits radiation of about 4.2 .mu.m wavelength. Embodiments in other material systems are possible, and the lasers can be readily designed to emit at a predetermined wavelength in a wide spectral region. We have designated the laser the "quantum cascade" (QC) laser. The QC laser comprises a multilayer semiconductor structure that comprises a multiplicity of essentially identical undoped "active" regions, a given active region being separated from an adjoining one by a doped "energy relaxation" region. In a currently preferred embodiment each active region comprises three coupled quantum wells designed to facilitate attainment of population inversion. In the currently preferred embodiment the energy relaxation regions are digitally graded gap regions. However, other energy relaxation regions are possible.

Abstract: The disclosed multi-pixel flat panel displays (e.g., flat panel field emission displays (FPFED) or liquid crystal displays (LCD)) includes spaced apart first and second electrodes, with a patterned solid material layer in contact with one of the electrodes, exemplarily between the two electrodes. The patterned layer (referred to as the "web") includes a multiplicity of apertures, with at least one (preferably three or more) aperture associated with a given pixel. In the aperture is disposed a quantity of a second material, exemplarily, a phosphor in the case of an FPFED, or a color filter material in the case of a LCD. The web can facilitate second material deposition by means of, e.g., screen printing, typically making possible formation of smaller phosphor or filter dots than was possible by prior art device. The web also can facilitate provision of spacer structure between the two electrodes, and can include getter or hygroscopic material.

Abstract: Novel superconductive oxides are disclosed. The oxides all have layered perovskite-like crystal structure and manifest superconductivity above about 77K. An exemplary material has composition Bi.sub.2.2 Sr.sub.2 Ca.sub.0.8 Cu.sub.2 O.sub.8. Other materials are described by the nominal formula X.sub.2+x M.sub.n-x Cu.sub.n-1 O.sub.2+2n+x/2.+-..delta., where X typically is Bi, or Bi together with Pb or other appropriate substituent, M is one or more divalent ion or mixture of monovalent and trivalent ion, n is an integer greater than 3, x=p/q, where p and q are integers and p<q, and .delta. is less than 0.5. Associated with the inventive compounds typically is a superlattice structure, with T.sub.c of the compound typically being correlated with the superlattice spacing. The inventive compounds are typically relatively ductile.

Abstract: The disclosed improved GaAs majority carrier rectifying barrier diodes comprise a p.sup.+ region between semiconductor regions that comprise n-doped material. Exemplary structures are n.sup.+ -i-p.sup.+ -i-n.sup.+ and n.sup.+ -n-p.sup.+ -n-n.sup.+. The improvement comprises use of carbon as the p-dopant and results in readily manufacturable reliable devices.

Abstract: An optical system useful, e.g., for near-field scanning optical microscopy is provided. The system incorporates a probe having improved properties. In one embodiment, the probe comprises a tapered and partially metallized portion of a single-mode optical fiber.

Abstract: A method is described for monitoring the rate at which metal layers are chemically etched. The method involves an indicator layer of metal formed on a surface of a monitor substrate. The thickness of the indicator layer varies according to a wedge-shaped profile along a longitudinal axis. The indicator layer is exposed to an etchant medium for a predetermined duration. During such exposure, a portion of the indicator layer is completely removed, exposing the underlying surface and creating an edge between the exposed surface and the remaining portion of the indicator layer. The etching rate is determined by reference to the longitudinal location of the edge.

Abstract: A scanning, imaging system is described. A probe having a fine tip is disposed adjacent the surface of a sample and scanned in a pattern lying in a plane substantially parallel to the surface. Means are provided for oscillating the probe tip, substantially within the scanning plane. Shear forces, acting upon the probe tip in a substantially lateral direction, cause changes in the oscillation of the probe tip. Such changes are detected by a position-sensitive photodetector.

Abstract: Unexpectedly large normalized refractive index changes (.DELTA.>10.sup.-5, but possibly even larger than 10.sup.-3) can be obtained in SiO.sub.2 -based optical waveguides (fiber or planar waveguides) by a treatment that comprises exposing at least a portion of the waveguide at a temperature of at most 250.degree. C. to H.sub.2 (partial pressure greater than 1 atmosphere), and irradiating at least a part of the exposed portion with actinic (typically UV) radiation.

Abstract: A novel method of making articles that comprise a periodic heteroepitaxial semiconductor structure is disclosed. The method pertains to growth of the periodic structure by MBE, CVD or similar growth techniques, and involves periodically changing the substrate temperature. For instance, a periodic multilayer GaAs/AlGaAs is grown by MBE, with the substrate temperature cycled between 600.degree. C. and 700.degree. C. The novel method can produce multilayer structures of uniformly high material quality.

Abstract: A method for forming elongated articles including metallic oxide superconductor material by hydrostatic extrusion at temperatures less than about 800.degree. C., and even at temperatures less than about 450.degree. C. The method includes providing superconductive core material that is substantially free of carbon or organic additives and that has an equivalent density at least about 55% of full density, and enclosing the densified material in a metal container, to become a cladding, prior to extrusion. In a preferred embodiment, the cladding material is a dispersion hardened metal or metal alloy.

Abstract: DFB lasers with advantageously structured grating region are disclosed. The grating region comprises one or more thin semiconductor layers (to be referred to as "QWs"), with the QWs varying periodically in the longitudinal direction of the laser. In an exemplary preferred embodiment the AWs are patterned during grating etch, with the topmost grating QW being covered with a layer of substantially the substrate composition. The structure inter alia facilitates defect-free epitaxial growth on the corrugated etched surface and also facilitates growth of the coupling coefficient .kappa.. Furthermore, lasers according to the invention can be partially or purely gain coupled, resulting in desirable wavelength discrimination.

Abstract: Disclosed are novel fast semiconductor photodetector means that comprise a good asymmetric superlattice structure. Associated with the material of the structure is a relatively short minority carrier effective lifetime .tau..sub.e, typically .tau..sub.e <10.sup.-9 sec. In response to a constant photon flux of appropriate wavelength the photodetector can have a substantially constant voltage output that is proportional to the photon flux for small values of flux, and that saturates at a value that is substantially proportional to .tau..sub.e.sup.-1 for relatively large values of flux. The novel photodetector means can be advantageously combined with a FET or bipolar transistor, and the combination can be part of an integrated circuit.

Abstract: Improved heterojunction bipolar transistor (HBT) are disclosed. Inventive devices can attain high cut-off frequency (f.sub.T), exemplarily 80 GHz or higher, and high DC current gain (.beta.), exemplarily 25 or higher. The devices exhibit lateral scaling, permitting reduction in emitter stripe width without unacceptable decrease in .beta.. Exemplarily the stripe width is 1 .mu.m or less. The inventive HBTs are hot electron devices, with the hot electrons in the base region being spatially confined such that relatively few electrons reach the surface of the extrinsic base region. The relatively low bulk and surface recombination rate in the base of inventive HBTs is an important aspect of the invention and makes possible devices having relatively high .beta. and low power consumption.