Abstract: An apparatus for non-destructively measuring resistivity of a semiconductor, such as InP, comprises light sources for illuminating a preselected portion of the semiconductor with first and second light beams, each of a preselected single wavelength, the first light beam operating to excite the semiconductor by photo injecting carriers, and the second light beam bombarding the local portion of the semiconductor with a preselected photon energy. The apparatus measures a fractional change in reflectance of the second light beam responsive to the first light beam, and records this fractional change in reflectance for various values of photon energy of the second light beam, to generate a photoreflectance line-shape. The photoreflectance line-shape is used to calculate a photoreflectance line-shape phase angle, which is used to determine the resistivity of the preselected portion of the semiconductor.

Abstract: An apparatus for measuring local carrier concentration in a preselected area of a semi-conductor is shown and described. An exciting light (preferably a laser) alters the sample's band-gap by photo injecting electron hole pairs in the area being measured. Because of the Franz-Keldysh effect, the photo injected carriers alter the sample's reflectivity. An optical fiber conducts a broad band source of probing light to the excited area on the sample. The sample reflects some of the broad band light back into a fiber that conducts the reflected light to an optical analyzer. The optical analyzer includes a dispersive element that disperses the reflected light onto a linear array of detectors. The analyzer thus simultaneously samples multiple wavelengths in the reflected spectrum. From the resulting samples, a computer deconvolutes the spectral line shape into a measurement of the local electric field and the local carrier concentration.

Abstract: An apparatus and method for non-destructive measuring of local carrier concentration and bandgap in a semiconductor such as gallium arsenide or gallium aluminum arsenide. A high energy source of photons, e.g. a laser, photo injects carriers on the surface of the semiconductor causing a change in the semiconductor's surface photo reflectance. The fractional change in photo reflectance is measured for a plurality of the photon energies sufficient to identify several Franz-Keldysh peaks, and the photon energies corresponding to these peaks. This information is used to infer the local electric field strength and carrier concentration of the semiconductor as well as semiconductor's bandgap. By noting variations in these parameters throughout the bulk semiconductor, one can identify fatal fabrication flaws in the semiconductor crystal before time and money is expended to fabricate complicated semiconductor architectures in the crystal.

Abstract: A method of preparing films having the formula A.sup.IIB B.sup.VIA wherein A.sup.IIB is a group IIB metal and B.sup.VIA is a chalcogenide by the photolysis or low temperature thermolysis of an organo-metallic compound containing the targeted A.sup.IIB B.sup.VIA elements is provided. Organo-metallic compounds utilized in the method are of the general formulas R-X-M-X-R', R-M-X-M-R', R-M-X-R', R-M-CH.sub.2 -X-R', R-M-X-X-R' wherein R and R' are hydrogen, an alkyl, an aryl or an organic radical containing a heteroatom, M is a group IIB metal and X is a chalcogenide. Photolysis is carried out with an ultraviolet, visible or infrared light source. The films are useful in the manufacture of semiconductor elements and optical coatings.

Abstract: A method for forming a single crystal epitaxial film of a selected metal on the surface of a substrate. The method includes the steps of positioning the substrate in an ultra high vacuum environment and exposing the substrate surface to a metalorganic vapor including ions of the selected metal while maintaining an ultra high vacuum environment.

Abstract: A semiconductor multi-color filter spectrum analyzer is created by multiple pitaxial layers of varying composition. A DC sweep voltage is used to successively deplete the epitaxial layers. An AC voltage is used to modulate the absorption edge of the individual layers.A modification of this device concept is a variable bandwidth detector in which the spectral bandwidth is a function of the applied DC voltage.

Abstract: A method and apparatus which permits photolysis of compounds without use of indows to permit unlimited growth of epitaxial layers. Epitaxial layers can include growth of crystals such as iron. A two section reactor chamber with a common opening between the sections is used for the internal production of high energy ultraviolet light to carry out the photolysis. The first section of the reactor chamber containing the substrate to be coated is connected to a source of molecular compound vapor capable of undergoing a photolytic change. A feed system provides a rare gas flow through the second section at low pressure past an electrode discharge system to produce ultraviolet light. The ultraviolet light passes through the opening between the sections and interacts with the molecular compound causing photolytic decomposition of the molecular compound and deposition of the desired epitaxial layer on the substrate.

Abstract: A quadrant avalanche photodiode with large surface areas is made using photolithographic planar technology. The use of proton bombardment creates semi-insulating material around the quadrants. Semi-insulating material prevents cross-talk between quadrants.The Schottky barrier quadrant detectors were fabricated using GaAs.sub.1-x Sb.sub.x ternary alloys grown epitaxially on heavily doped GaAs substrates.

Abstract: A semi-conductor multi-color tunable filter is created by multiple epitaxial layers of varying composition. An AC modulation voltage is superimposed on a sweep bias to periodically shift the fundamental absorption edge of each individual epitaxial layer. This arrangement permits a unique voltage to be associated with a particular color. A lock-in filter matches colors observed at a detector with the voltage present for a given observation.

Abstract: A narrow two color semiconductor detector created from the built in field tween epitaxial layers due to interface traps. Opposite polarity on opposite sides of the interface result in a net photocurrent created on each side which flows in opposing directions. The substrate supporting the epitaxial layers provides a cutoff filter range for light entering through the substrate.

Abstract: A method of and apparatus for measuring lattice mismatch in a thin multilr semiconductor. By changing the voltage potential across a semiconductor, the different energy gaps present will absorb different frequencies of light. By shining monochromatic light of the frequency in question, a detector can observe the presence of such energy gaps by the absorption of the instant light intensity that will occur. The use of a Schottky barrier permits the light to be reflected back through the device a second time to maximize the absorption characteristics of energy gaps which may be present. Use of a substrate with known energy gaps permits broad band light to be scanned to determine the spectral components absorbed at each of the known energy gaps within the semiconductor.

Abstract: An infrared detector with narrow band tunable response. The detector is cosed of four layers of epitaxially grown material that is doped for selective wavelength absorption. The uppermost layer has a thickness much larger than the penetration depth of short wavelength radiation or the diffusion length of photo generated carriers near the surface. The upper layer is a heavily N-doped layer over a P-doped layer. The cut-on wavelength edge is determined by the amount of doping in the uppermost layer. By applying a reverse bias to this N-P junction, the cut-off absorption edge can be shifted to longer wavelengths.

Abstract: A data bus coupler having a fiber optic bundle input, a separate optical ulator or detector (described in a concurrent disclosure by the same inventors) attached to each fiber of the bundle for adding information to, extracting information from, or detecting the information conducted by the fiber, and an output wherein the fibers are rejoined into a fiber optic bundle. The optical modulator/detectors are double heterojunction semiconductors that are switched "on" by reverse biasing and with large voltages they may act as photoavalanche diodes when detecting incident radiation.

Abstract: A tunable, electroabsorptive, semiconductor detector or detector-modulator for detecting or modulating radiation near the absorptive edge of the detector, which edge can be tunably shifted by back biasing.

Abstract: A dye laser having a high frequency rate of modulation wherein a Franz-Kesh filter is in the laser cavity to quench Q, and thereby provide modulation. The filter has an absorption edge that shifts in response to an applied electric field, thereby, modulating the laser beam.