Abstract: The invention provides a means for preparing rare-earth-doped ?-(Al1-xGax)2O3 films by molecular beam epitaxy (MBE). The invention provides a composition of matter, rare-earth-doped ?-(Al1-xGax)2O3 films, and methods to provide thin films of this material. The invention also provides a means to prepare thin film rare-earth-doped ?-(Al1-xGax)2O3, including Nd: ?-(Al1-xGax)2O3, for use in solid state lasers. Rare-earth-doped ?-Ga2O3 and rare-earth-doped alloys of ?-Ga2O3 and ?-Al2O3 with the same single-crystal structure independent of Ga/Al ratio are disclosed herein.

Abstract: The present invention relates to the growth of single phase rare earth-doped sapphire (?-Al2O3) films on substrates by molecular beam epitaxy. The invention provides for composition of matters, neodymium-doped sapphire films, and methods for making and using thin films of this material. The rare earth-doped films of the present invention are especially useful in solid state lasers.

Abstract: The invention relates to methods of making optical waveguide structures by way of molecular beam epitaxy (MBE). The method comprises the steps of: (1) providing a single crystal substrate in an ultra-high vacuum (UHV) environment, wherein the single crystal substrate has a first index of refraction; (2) heating the single crystal substrate; (3) depositing an epitaxial oxide layer having a rare-earth dopant and a second index of refraction on the single crystal substrate, wherein the epitaxial oxide layer is deposited by way of at least first, second, and third molecular beam fluxes; and (4) depositing a cladding layer on the single crystal oxide layer, wherein the cladding layer has a third index of refraction that is the same or about the same as the first index of refraction of the single crystal substrate, and wherein the second index of refraction is greater than the first and third indexes of refraction.

Abstract: An optical method for measuring the temperature of a substrate material with a temperature dependent band edge. In this method both the position and the width of the knee of the band edge spectrum of the substrate are used to determine temperature. The width of the knee is used to correct for the spurious shifts in the position of the knee caused by: (i) thin film interference in a deposited layer on the substrate; (ii) anisotropic scattering at the back of the substrate; (iii) the spectral variation in the absorptance of deposited layers that absorb in the vicinity of the band edge of the substrate; and (iv) the spectral dependence in the optical response of the wavelength selective detection system used to obtain the band edge spectrum of the substrate. The adjusted position of the knee is used to calculate the substrate temperature from a predetermined calibration curve.

Abstract: A method and apparatus for facilitating controllable switching an interface between a reflective state in which light incident upon the interface undergoes total internal reflection, and a non-reflective state in which total internal reflection is prevented at the interface. The apparatus incorporates a member (preferably an elastomer) which is deformable with respect to the interface. The member's Young's Modulus in portions of the member adjacent the interface is substantially greater (i.e. stiffer) than the member's Young's Modulus in portions of the member away from the interface. The stiffened portion of the member adjacent the interface may be in the form of a microstructure. A pair of electrodes coupled to a voltage source can be provided to controllably deform the member into optical contact with the interface, within a continuously variable range of optical contact values, to produce the non-reflective state in selectably varying degrees.

Abstract: An optical method for measuring the temperature of a substrate material with a temperature dependent bandgap. The substrate is illuminated with a broad spectrum lamp and the bandgap is determined from the spectrum of the diffusely scattered light. The spectrum of the light from the lamp is sufficiently broad that it covers the spectral range above and below the bandgap of the substrate. Wavelengths corresponding to photon energies less than the bandgap of the substrate are transmitted through the substrate and are reflected from the back surface of the substrate as well as from the front surface while the wavelengths corresponding to photon energies larger than the bandgap are reflected only from the front surface. If the front surface is polished the front surface reflection will be specular while if the back surface is rough the reflection from the back surface will be non-specular. The back surface reflection is detected with a detector in a non-specular location.

Abstract: An optical method and apparatus for measuring the temperature of a substrate material with a temperature dependent bandgap. The substrate is illuminated with a broad spectrum lamp and the bandgap is determined from the spectrum of the diffusely scattered light. The spectrum of the light from the lamp is sufficiently broad that it covers the spectral range above and below the bandgap of the substrate. Wavelengths corresponding to photon energies less than the bandgap of the substrate are transmitted through the substrate and are reflected from the back surface of the substrate as well as from the front surface while the wavelengths corresponding to photon energies larger than the bandgap are reflected only from the front surface. If the front surface is polished the front surface reflection will be specular while if the back surface is rough the reflection from the back surface will be non-specular. The back surface reflection is detected with a detector in a non-specular location.

Abstract: A method for making a layered metal chalcogenide catalyst wherein the catalyst has a crystalline structure with increased edge sites produced by lithographic methods.

Abstract: A high surface area substrate with controlled pore size and slot geometry is made by depositing at least two materials in alternating layers. The film is then broken up and one of the materials is etched away to produce a slotted surface structure. These slots can add size and shape selectively to separations and catalytic processes which because of the uniform and controllable dimensions (>5A) would be superior to that obtainable from zeolites and clays.

Abstract: The present invention is an X-ray mirror including a multi-layered material in which the composition of the layers repeat, the repeat distance being between 8 and 250 A., In one embodiment, the mirror is produced by CVD. In another embodiment, the layers forming the structure are made of amorphous semiconductor or insulator material.

Abstract: A semiconductor device which includes an active region including a superlattice amorphous material wherein the energy gap has a predetermined value. A preferred embodiment of the device is a solar cell. In another embodiment of the present invention, the device is a tandem solar cell which includes a first active region including a superlattice material wherein the bandgap has a first predetermined value; a second active region including a second superlattice material wherein the bandgap has a second predetermined value different from said first predetermined value; a means for electrically interconnecting said first and second active regions such that current may flow between said first and second active regions.

Abstract: A contactless rf technique for measurement of the carrier lifetime from the photoconductivity induced in silicon wafers by a flash of infrared light. The carrier lifetime is inferred from the photoconductivity decay.

Abstract: The present invention teaches a combination of parameters for the glow discharge decomposition of silane deposition of an amorphous silicon semiconductor having non-dispersive high mobility transport of majority carriers through the semiconductor material, useful in switching devices such as diodes, transistors and the like.

Abstract: A thin film semiconductor device with enhanced optical absorption properties and a method for producing it. The device comprises a substrate having at least one sandblasted surface and a thin film of semiconductor material deposited on the sandblasted surface.