Abstract: Electrically controlled solid-state thermal switches and methods of controlling heat flow. An electrostrictive material is electromagnetically coupled to first and second electrodes that provide an electric field to the electrostrictive material. Different portions of the electrostrictive material are thermally coupled to each of a heat sink and a thermal load so that heat flowing from one into the other passes through the electrostrictive material. A control voltage is applied to the electrodes to selectively generate the electric field, thereby selectively altering the thermal conductivity of the electrostrictive material. The heat sink and thermal load are thereby selectively thermally coupled to each other in dependance on the control voltage.

Abstract: Thermoelectric devices and methods of using thermoelectric devices. A thermoelectric device includes a thermoelectric element comprised of a material having a non-zero Berry curvature. The device may operate as a Nernst generator that generates electricity in response to application of a temperature gradient to the thermoelectric element, or as an Ettingshausen cooler that pumps heat into or out of an object to be heated or cooled in response to application of a current to the thermoelectric element. In either application, the non-zero Berry curvature of the material allows the device to operate without an externally applied magnetic field.

Abstract: Thermoelectric devices and methods of using thermoelectric devices. A thermoelectric device includes a thermoelectric element comprised of a material having a non-zero Berry curvature. The device may operate as a Nernst generator that generates electricity in response to application of a temperature gradient to the thermoelectric element, or as an Ettingshausen cooler that pumps heat into or out of an object to be heated or cooled in response to application of a current to the thermoelectric element. In either application, the non-zero Berry curvature of the material allows the device to operate without an externally applied magnetic field.

Abstract: Thermoelectric devices and methods of using thermoelectric devices. A thermoelectric device includes a thermoelectric element comprised of a material having a non-zero Berry curvature. The device may operate as a Nernst generator that generates electricity in response to application of a temperature gradient to the thermoelectric element, or as an Ettingshausen cooler that pumps heat into or out of an object to be heated or cooled in response to application of a current to the thermoelectric element. In either application, the non-zero Berry curvature of the material allows the device to operate without an externally applied magnetic field.

Abstract: A position sensor comprises a group III-nitride Hall effect sensor arranged to measure magnetic field from a magnet wherein the group III-nitride Hall effect sensor and the magnet are arranged to move relative to one another in response to movement of an element whose motion is to be monitored. The electrically conductive layer of the group III-nitride Hall effect sensor may comprise a two-dimensional electron gas (2DEG) defined by an AlxGa1-xN/GaN interface where x>0 and in some embodiments x=1 (i.e. an A1N/GaN interface). Disclosed position measurement methods comprise measuring position or speed of the element being monitored using such a position sensor in an environment at a temperature of at least 300° C., and in some embodiments at least 350° C.

Abstract: A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi1-xSbx)u(Te1-ySey)w, wherein 0?x?1, 0?y?1, 1.8?u?2.2, 2.8?w?3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments, the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.

Abstract: A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi1-xSbx)u(Te1-ySey)w, wherein 0?x?1, 0?y?1, 1.8?u?2.2, 2.8?w?3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments, the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.

Abstract: A thermoelectric material and a method of using a thermoelectric device are provided. The thermoelectric material includes at least one compound having a general composition of (Bi1-x-zSbxAz)u(Te1-ySey)w. The component A includes at least one Group IV element, and the other components are in the ranges of 0?x?1, 0?y?1, 0<z?0.10, 1.8?u?2.2, and 2.8?w?3.2. The method of using a thermoelectric device can include exposing the thermoelectric material to a temperature greater than about 173 K.

Abstract: A thermoelectric material and a method of fabricating a thermoelectric material are provided. The thermoelectric material includes a compound having an elemental formula of A1?xB1+yC2+z and having a coefficient of thermal expansion greater than 20 parts-per-million per degree Celsius in at least one direction at one or more operating temperatures. The A component of the compound includes at least one element selected from the group consisting of: at least one Group Ia element and at least one Group Ib element, the B component of the compound includes at least one element selected from the group consisting of: at least one Group V element and at least one Group VIII element, and the C component of the compound includes at least one Group VI element. In addition, x is between ?0.2 and 0.3, y is between ?0.2 and 0.4, and z is between ?0.2 and 0.8.

Abstract: A thermoelectric material and a method of fabricating a thermoelectric material are provided. The thermoelectric material includes a doped compound of at least one Group IV element and at least one Group VI element. The compound is doped with at least one dopant selected from the group consisting of: at least one Group Ia element, at least one Group IIb element, at least one Group IIIa element, at least one Group IIIb element, at least one lanthanide element, and chromium. The at least one Group IV element is on a first sublattice of sites and the at least one Group VI element is on a second sublattice of sites, and the at least one Group IV element includes at least 95% of the first sublattice sites. The compound has a peak thermoelectric figure of merit ZT value greater than 0.7 at temperatures greater than 500 K.

Abstract: A magnetic field sensor apparatus that comprises an active layer of indium antimonide or indium arsenide supported on an elemental semiconductor substrate. Magnetoresistor sensors of indium antimonide and indium arsenide active layers on silicon and germanium substrate wafers are described. Means are described for providing reduced electric fields and parasitic conduction in the elemental semiconductor substrate. The means includes unique device geometries and buffer layers between the active layers and the substrate wafers.

Abstract: Films of hexagonal boron nitride are converted to a highly desirable cubic-like phase of boron nitride. The transformation is achieved by annealing the hBN material at temperatures below 1000.degree. C. The conversion may be conducted in a hydrogen, nitrogen, ammonia, vacuum, or inert gas containing atmosphere.

Abstract: A semiconductor film is provided characterized by having high carrier mobility and carrier density. The semiconductor film is doped with the rare-earth element erbium so as to improve its temperature stability. The semiconductor film is thereby particularly suited for use as a magnetic field sensing device, such as a Hall effect sensor or magnetoresistor. The semiconductor film is formed from a narrow-gap Group III-V compound, preferably indium antimonide, which is n-doped with the erbium to provide an electron density sufficient to increase temperature stability. In particular, the semiconductor film is characterized by a nini-structure which is generated using a slab-doping technique. The slab-doping process encompasses the growing of alternating layers of doped and undoped layers of the Group III-V compound, with the doped layers being substantially thinner than the undoped layers, and preferably as thin as one atomic plane.

Abstract: A multilayer structure for use in forming a transistor which may be suitable for high temperature applications is provided. A single crystal silicon substrate has an overlaying layer of epitaxially grown cubic boron nitride in crystallographic registry with the silicon substrate. The cubic boron nitride is epitaxially grown using laser ablation techniques and provides an electrically resistive and thermally conductive barrier. An active layer of epitaxial silicon is then grown from the layer of cubic boron nitride, such that the overlaying layer of epitaxial silicon is in crystallographic registry with the layer of boron nitride which is in crystallographic registry with the underlying silicon substrate. Appropriately doped source and drain regions and a gate electrode are provided to form the transistor.

Abstract: A magnetic field sensor, such as a magnetoresistor, having improved electron mobility comprises a substrate of an insulating semiconductor material, such as gallium arsenide or indium phosphide, having on a surface thereof a narrow strip of a thin active film. The active film has a thin first layer of undoped or lightly doped high electron mobility semiconductor material, such as indium antimonide or indium arsenide, on the substrate surface, and a second layer of the semiconductor material, which may be thicker than the first layer, on the first layer. The second layer is at least partially doped n-type conductivity so as to have a high electron density. The second layer may be entirely of the n-type conductivity semiconductor material or a superlattice of alternating layers of n-type conductivity and intrinsic semiconductor materials or a superlattice of intrinsic semiconductor material and a ternary or quaternary alloy of the semiconductor material which is at least partially of n-type conductivity.

Abstract: A Hall generator includes a substrate body of single crystalline semi-insulating gallium arsenide having a surface. A thin layer, no greater than about 5 micrometers in thickness, of single crystalline indium arsenide is on the surface of the body and is in the form of four arms joined at a common point to form a cross. A separate metal contact is on each of the arms at the free end thereof. An accumulation layer is adjacent the outer surface of the indium arsenide layer and extends along the entire surface of the indium arsenide layer between the contacts. The accumulation layer is effective to provide a magnetic sensitivity and range of operating temperatures as if the indium arsenide layer was much thinner and had a much higher electron density and electron mobility. Electrical devices, such as field effect transistors, may be formed in the body and the surface and electrically connected to the contacts of the Hall generator in a desired circuit.

Abstract: A magnetic field sensor, such as a magnetoresistor, Hall effect device or magnetotransistor, comprising an active layer of indium antimonide on the surface of a substrate having a length substantially greater than its width. A conductive contact is on the active layer at each end thereof and a plurality of shorting bar contacts are on the active layer and spaced along the length of the active layer between the end contacts. The contacts are each of a thin layer of a highly conductive n-type conductivity semiconductor material which has a low sheet resistivity and a low contact resistance with the active layer. A layer of a conductive metal may be provided on the semiconductor material layer of the contact, and a thin layer of highly conductive n-type indium antimonide may be provided between the semiconductive material layer and the active layer.

Abstract: A multilayer structure for use in forming a transistor which may be suitable for high temperature applications is provided. A single crystal silicon substrate has an overlaying layer of epitaxially grown cubic boron nitride in crystallographic registry with the silicon substrate. The cubic boron nitride is epitaxially grown using laser ablation techniques and provides an electrically resistive and thermally conductive barrier. An active layer of epitaxial silicon is then grown from the layer of cubic boron nitride, such that the overlaying layer of epitaxial silicon is in crystallographic registry with the layer of boron nitride which is in crystallographic registry with the underlying silicon substrate. Appropriately doped source and drain regions and a gate electrode are provided to form the transistor.

Abstract: A magnetoresistive sensor that includes a thin film of nominally undoped monocrystalline indium arsenide. An indium arsenide film is described that appears to have a naturally occurring accumulation layer adjacent its outer surface. With film thicknesses below 5 micrometers, preferably below 3 micrometers, the presence of the accumulation layer can have a very noticeable effect. A method for making the sensor is also described. The unexpected improvement provides a significant apparent increase in mobility and conductivity of the indium arsenide, and an actual increase in magnetic sensitivity and temperature insensitivity.

Abstract: A method for forming a transistor which may be suitable for high temperature application is provided. A single crystal silicon substrate has an overlaying layer of epitaxially grown cubic boron nitride in crystallographic registry with the silicon substrate. The cubic boron nitride is epitaxially grown using laser ablation techniques and provides an electrically resistive and thermally conductive barrier. An active layer of epitaxial silicon is then grown from the layer of cubic boron nitride, such that the overlaying layer of epitaxial silicon is in crystallographic registry with the layer of boron nitride which is in crystallographic registry with the underlying silicon substrate. Appropriately doped source and drain regions and a gate electrode are provided to form the transistor.