Abstract: A planar avalanche photodetector (APD) is fabricated by forming a, for example, InGaAs absorption layer on a p+-type semiconductor substrate, such as InP, and wafer-bonding to the absorption layer a second p-type semiconductor, such as Si, to form a multiplication layer. The layer thickness of the multiplication layer is substantially identical to that of the absorption layer. A region in a top surface of the p-type Si multiplication layer is doped n+-type to form a carrier separation region and a high electric field in the multiplication region. The APD can further include a guard-ring to reduce leakage currents as well as a resonant mirror structure to provide to wavelength selectivity. The planar geometry furthermore favors the integration of high-speed electronic circuits on the same substrate to fabricate monolithic optoelectronic transceivers.

Abstract: The method of the present invention is used to join two dissimilar materials together, and particularly to transfer a film to a substrate when the difference in thermal expansion coefficients between the film and the substrate is very big. A hydrophilic surface is created on one material and an atmosphere reactive metal element is deposited on the surface of another material. When the materials are tightly contacted, with the reactive element pressed against the hydrophilic surface, the reactive metal element reacts with the moisture from the hydrophilic surface at room temperature. Strong bonds form during the reaction joining the two materials together. Because the procedure takes place at room temperature, extremely low stress is built in. The film joining is successful even with a big thermal expansion coefficient difference between the materials, such as exist between GaAs and silicon and between silicon and sapphire.

Abstract: Two-terminal circuit has top and bottom cells bonded to an insulating substrate with the top cells bonded on top of the bottom cells. Bottom cells are connected in series through ribbon bonds. Top cells are connected in parallel through ribbon bonds. The ribbon bonds connect to the topsides of the top and bottom cells. The substrate contains metal die bonding pads for the base contacts to the bottom cells. Metal traces are provided for ribbon bond connections to emitter contacts for the bottom cells. A metal trace becomes a positive terminal pad for the bottom cells and a negative terminal for a second pad for the bottom cells. Two cell assemblies may be series connected by connecting positive top cell output connectors with negative pads of top cells in adjacent cell assemblies, and by connecting positive bottom cell output connectors with negative pads of bottom cells in adjacent assemblies.

Abstract: A compact forced air cooled thermophotovoltaic generator includes a TPV converter assembly, a fan which is driven by electric power generated by the converter assembly and a housing for enclosing the assembly and fan. The assembly includes a fuel/air mixing tube, an infrared emitter positioned in the combustion chamber, a receiver positioned around the emitter and a heat shield positioned between the receiver and the emitter. The receiver includes a circuit having TPV cells connected to an inner surface and radial fins extending from an outer surface. A fuel source may be provided proximate (i.e. beneath) the mixing tube or may be remotely connected to the mixing tube by a fuel line. A housing encloses the TPV converter assembly and the fuel source, if provided as part of the unit. A fan or other updraft mechanism electrically connected to the cell circuit is provided at the bottom of the housing beneath the fuel source and/or converter assembly.

Abstract: A method of semiconductor eutectic alloy metal (SEAM) technology for integration of heterogeneous materials and fabrication of compliant composite substrates takes advantage of eutectic properties of alloys. Sub1 and Sub2 are used to represent the two heterogeneous materials to be bonded or composed into a compliant composite substrate. For the purpose of fabricating compliant composite substrate, the first substrate material (Sub1) combines with the second substrate material (Sub2) to form a composite substrate that controls the stress in the epitaxial layers during cooling. The second substrate material (Sub2) controls the stress in the epitaxial layer grown thereon so that it is compressive during annealing. A joint metal (JM) with a melting point of Tm is chosen to offer variable joint stiffness at different temperatures. JM and Sub1 form a first eutectic alloy at a first eutectic temperature Teu1 while JM and Sub2 form a second eutectic alloy at a second eutectic temperature Teu2.

Abstract: A method for producing a stress-engineered substrate includes selecting first and second materials for forming the substrate. An epitaxial material for forming a heteroepitaxial layer is then selected. If the lattice constant of the heteroepitaxial layer (aepi) is greater than that (asub) of the immediate substrate layer the epitaxial layer is deposited on, then the epitaxial layer is kept under “compressive stress” (negative stress) at all temperatures of concern. On the other hand, if the lattice constant of the heteroepitaxial layer (aepi) is less than that (asub) of the immediate substrate layer the epitaxial layer is deposited on, then the epitaxial layer is kept under “tensile stress” (positive stress). The temperatures of concern range from the annealing temperature to the lowest temperature where dislocations are still mobile.

Abstract: A shingle circuit array and a method of assembling the shingle circuit is provided. The array has a shingle circuit with a substrate, an insulation film layer, a metal layer and TPV cells connected to the metal layer in series forming a shingle pattern with terraces. The substrate is of CTE matched material. The metal layer may be copper pads deposited on the terraces. The TPV cells are bonded to the copper pads and may be GaSb cells. Substrate materials include AlSiC or a Cu/Invar/Cu laminate sheet. The AlSiC material may be a microstructure having a continuous Al-metal phase with a discrete SiC particulate phase. The substrate may also be an enameled cast-iron substrate. The shingle circuit array may be provided in a TPV generator.

Abstract: The present invention is a hydrocarbon fired thermophotovoltaic furnace having a non-fused silica tube. In a preferred embodiment, the furnace has an infrared emitter tube having a top end and a bottom end and a substantially transparent non-fused silica window tube having a closed top end. The window tube is positioned concentrically around the infrared emitter tube, and the infrared emitter tube is in fluid communication with the window tube. The window tube is preferably composed of Lucalox (alumina or Chromolux), magnesia, yterria, titania, spinel, stablized zirconia or yterria alumina garnet. In another preferred embodiment, the furnace has a radiator tube having a top end and a bottom end and an infrared emitter tube having a closed top end. The infrared emitter tube is positioned concentrically around the radiator tube, and the radiator tube is in fluid communication with the infrared emitter tube. Fluid flows from the inner tube to the outer tube.

Abstract: Thermophotovoltaic (TPV) electric power generators have emitters with infrared (IR) outputs matched with usable wavelengths for converter cells. The emitters have durable substrates, optional refractory isolating layers, conductive refractory metal or inter-metallic emitter layers, and refractory metal oxide antireflection layers. SiC substrates have tungsten or TaSi2 emitter layers and 0.14 micron HfO2, ZrO2, Al2O3, Ta2O5 and TiO2 antireflection layers used as IR emitters for GaSb converter cells in TPV generators.

Abstract: A shingle circuit array and a method of assembling the shingle circuit is provided. The array has a shingle circuit with a substrate, an insulation film layer, a metal layer and TPV cells connected to the metal layer in series forming a shingle pattern with terraces. The substrate is of CTE matched material. The metal layer may be copper pads deposited on the terraces. The TPV cells are bonded to the copper pads and may be GaSb cells. Examples of substrate materials include AlSiC or a Cu/Invar/Cu laminate sheet. The AlSiC material may be a microstructure having a continuous Al-metal phase with a discrete SiC particulate phase. The shingle circuit array may be provided in a TPV generator.

Abstract: A small and light cylindrical thermophotovoltaic generator uses gaseous fuels, a counter flow heat exchanger, regenerator and low bandgap photovoltaic cells. In the fuel injection system, with preheated air from a recuperator, fuel combustion begins immediately when the fuel and air first meet. A hot and compact burn results from complete and rapid fuel and air mixing. A venturi necks down the air flow, and a chemically etched jet shim disk creates over 150 small fuel jet streams. The emitter geometric configuration provides good hot gas energy transfer to the IR emitter. Four alternate emitter configurations accomplish the good heat transfer. One emitter is a composite SiC with integrally formed internal fins which extend into the combustion chamber. The photovoltaic converter assembly has good spectral control, good high rate but lightweight heat removal and high current-carrying capability, while maintaining low parasitic IR absorption.

Abstract: A method of semiconductor eutectic alloy metal (SEAM) technology for integration of heterogeneous materials and fabrication of compliant composite substrates takes advantage of eutectic properties of alloys. Sub1 and Sub2 are used to represent the two heterogeneous materials to be bonded or composed into a compliant composite substrate. For the purpose of fabricating compliant composite substrate, the first substrate material (Sub1) combines with the second substrate material (Sub2) to form a composite substrate that controls the stress in the epitaxial layers during cooling. The second substrate material (Sub2) controls the stress in the epitaxial layer grown thereon so that it is compressive during annealing. A joint metal (JM) with a melting point of Tm is chosen to offer variable joint stiffness at different temperatures. JM and Sub1 form a first eutectic alloy at a first eutectic temperature Teu1 while JM and Sub2 form a second eutectic alloy at a second eutectic temperature Teu2.

Abstract: Thermophotovoltaic (TPV) electric power generators have emitters with infrared (IR) outputs matched with usable wavelengths for converter cells. The emitters have durable substrates, optional refractory isolating layers, conductive refractory metal or inter-metallic emitter layers, and refractory metal oxide antireflection layers. SiC substrates have tungsten or TaSi2 emitter layers and 0.14 micron ZrO2 or Al2O3 antireflection layers used as IR emitters for GaSb converter cells in TPV generators.

Abstract: A three-layer solid infrared emitter having a spectral output matched to low bandgap TPV cells is provided. The three layers include inner and outer layers, and a core layer between the inner and outer layers. The core layer is of solid fiber reinforced undoped refractory oxide material. The inner layer of siC material absorbs radiation from the radiator, the core layer conducts heat from the inner layer to the outer layer. The core layer is a strengthening layer forming a diffuse reflector for stopping a shine-through of long wavelength radiation from the inner layer thereby preserving spectral selectivity in the outer layer. The emitter material may be cobalt doped, nickel doped, or combination of Ni or Co doped refractory oxides with erbia or a thin erbia selective emitter layer.

Abstract: A TPV cell apparatus with a base region of GaSb crystals. The GaSb crystals are of varying orientations and joined at grain boundaries. A surface region is provided on the GaSb crystals. The GaSb crystals are Tellurium doped N-type GaSb and the surface region is thin Zinc doped P-type GaSb cells. The surface region faces an infrared source. A bus region is connected to a metal grid connected which is in contact with the surface region of the cell. A continuous metal layer is in contact with the GaSb crystals. A multilayer coating is provided on a front side of the cell. The multilayer coating forms an infrared filter for transmitting convertible infrared energy to the cell and for reflecting as much of non-convertible infrared energy back to the IR source as possible. A TPV generator may be provided with the TPV cells.

Abstract: The TPV generator unit insert has air circulation fans that supply air for both TPV cell cooling and heat transfer and room air circulation. Combustion air is supplied by a blower and mixed with natural gas or propane in a mixing chamber. Fuel and air mixing is enhanced by injecting the fuel counter to the air flow in an air supply tube within the mixing chamber. The fuel and air mixture is then injected into a combustion chamber and burned. The hot combustion gases then heat an IR emitter. Infrared radiation from the emitter is then incident on TPV cells, where electricity is produced. The hot by-product gases then transfer heat to the circulating room air in an upper plenum prior to exiting the room through the flue pipe. The yellow-orange glow from the emitter is visible through a front glass window, which then produces a very aesthetically pleasing effect. The rectangular unit is designed to include at least two cell panels at front and at the back.

Abstract: A thermophotovoltaic generator apparatus includes a thermophotovoltaic converter assembly and a cooling fan positioned beneath the assembly for generating an updraft around the assembly. A fuel source is connected to the converter assembly by a fuel line. A new control system, which may include a non-metallic electrode for flame sensing and, regulates flow of fuel from the fuel source to the converter assembly. A housing encloses the cooling fan and the converter assembly. The converter assembly includes a fuel injector cup having a fuel inlet connected to the fuel source and a fuel outlet. A combustion chamber is positioned above the cup for receiving fuel from the fuel outlet and for allowing hydrocarbon combustion. A combustion fan is positioned between the cup and the cooling fan for generating an updraft into the combustion chamber. An infrared emitter is positioned around the combustion chamber for emitting infrared radiation when heated by combustion gases resulting from the hydrocarbon combustion.

Abstract: A thermophotovoltaic generator includes an infrared cobalt oxide doped refractory ceramic emitter having a broad power band region which is matched with the energy conversion band of a low bandgap thermophotovoltaic cell receiver. The generator is provided with a heat source or is constructed for mounting on a heat source or for holding a heat source, such as a radioisotope. The generator is compatible with any heat source, including, but not limited to, a hydrocarbon flame, nuclear reactors, and radioisotopes. The emitter is made of a refractory ceramic material such as cobalt oxide doped alumina or magnesia. The refractory compound of the emitter is preferably doped with a small number of substitutional ions to create a material for emitting near blackbody radiation in a wide wavelength band above a threshold energy level and a minimal amount of radiation at wavelengths longer than the threshold level.

Abstract: A multilayered thermochromic display system is provided, wherein a thermochromic substance is applied to inert films in stacked layers with a non-invasive barrier between each layer of thermochromic substance. The thermochromic substance in each layer responds in a different temperature range so that as the temperature changes, the display exhibits repeated sequences of colors. The use of multiple layers with different temperature sensitivities enables the use of the displays over a broad range of temperatures.

Abstract: An electrical circuit for generating a polynomial function in response to a linear input signal is disclosed. The circuit in one embodiment comprises a primary and a secondary current mirror, with the collector or source of the secondary current mirror connected in common with the input signal of the primary current mirror. The output signal of the electrical circuit is taken at the mirrored current source terminal of the first current mirror. The primary and secondary current mirrors are biased to at least initially respond exponentially to the linear input signal. Each then transitions into the more linear, resistor-dominated range. The primary current mirror is enabled at a predetermined cut-in level, such that an upward curving exponential response function is generated in response thereto.