242 results about "Active structure" patented technology

A high electron mobility transistor (HEMT) is disclosed that includes a semi-insulating silicon carbide substrate, an aluminum nitride buffer layer on the substrate, an insulating gallium nitride layer on the buffer layer, an active structure of aluminum gallium nitride on the gallium nitride layer, a passivation layer on the aluminum gallium nitride active structure, and respective source, drain and gate contacts to the aluminum gallium nitride active structure.

Exemplary embodiments provide semiconductor devices including high-quality (i.e., defect free) group III-N nanowires and uniform group III-N nanowire arrays as well as their scalable processes for manufacturing, where the position, orientation, cross-sectional features, length and the crystallinity of each nanowire can be precisely controlled. A pulsed growth mode can be used to fabricate the disclosed group III-N nanowires and / or nanowire arrays providing a uniform length of about 10 nm to about 1000 microns with constant cross-sectional features including an exemplary diameter of about 10-1000 nm. In addition, high-quality GaN substrate structures can be formed by coalescing the plurality of GaN nanowires and / or nanowire arrays to facilitate the fabrication of visible LEDs and lasers. Furthermore, core-shell nanowire / MQW active structures can be formed by a core-shell growth on the nonpolar sidewalls of each nanowire.

A SERS-active structure is disclosed that includes a substrate and at least one nanowire disposed on the substrate. The at least one nanowire includes a core including a first material and a coating including a SERS-active material. A SERS system is also disclosed that includes a SERS-active structure. Also disclosed are methods for forming a SERS-active structure and methods for performing SERS with SERS-active structures.

Fuel cell devices and fuel cell systems, methods of using same, and methods of making same are provided. In certain embodiments, the fuel cell devices may include one or more active layers containing active cells that are connected electrically in parallel and / or series. In certain embodiments, the fuel cell devices include an elongate ceramic support structure the length of which is the greatest dimension such that the coefficient of thermal expansion has only one dominant axis coextensive with the length. In certain embodiments, a reaction zone is positioned along a first portion of the length for heating to a reaction temperature, and at least one cold zone is positioned along a second portion of the length for operating below the reaction temperature. There are one or more gas passages, each having an associated anode or cathode. In some embodiments, ceramic end tubes are permanently attached to the ceramic support structure to supply gases to the passages. In certain embodiments, a multilayer active structure is attached upon a flat tube having a plurality of channels therein for feeding gases into the passages of the multilayer active structure. In other embodiments, multilayer active structures are provided in which the electrodes contain pluralities of microtubular or nanotubular passages for feeding gases thereto. In yet other embodiments, the multilayer active structure is contained within a ceramic support structure that includes two elongate members that extend outwardly from one edge for feeding gases into the multilayer active structure.

Methods of forming NERS-active structures are disclosed that include ordered arrays of nanoparticles. Nanoparticles covered with an outer shell may be arranged in an ordered array on a substrate using Langmuir-Blodgett techniques. A portion of the outer shell may be removed, and the exposed nanoparticles may be used in a system to perform nanoenhanced Raman spectroscopy. An ordered array of nanoparticles may be used as a mask for forming islands of NERS-active material on a substrate. NERS-active structures and an NERS system that includes an NERS-active structure are also disclosed. Also disclosed are methods for performing NERS with NERS-active structures.

A NERS-active structure includes a deformable, active nanoparticle support structure for supporting a first nanoparticle and a second nanoparticle that is disposed proximate the first nanoparticle. The nanoparticles each comprise a NERS-active material. The deformable, active nanoparticle support structure is configured to vary the distance between the first nanoparticle and the second nanoparticle while performing NERS. Various active nanoparticle support structures are disclosed. A NERS system includes such a NERS-active structure, a radiation source for generating radiation scatterable by an analyte located proximate the NERS-active structure, and a radiation detector for detecting Raman scattered radiation scattered by the analyte. A method for performing NERS includes providing such a NERS-active structure, providing an analyte at a location proximate the NERS-active structure, irradiating the NERS-active structure and the analyte with radiation, varying the distance between the nanoparticles, and detecting Raman scattered radiation scattered by the analyte.

Embodiments provide a quantum dot active structure and a methodology for its fabrication. The quantum dot active structure includes a substrate, a plurality of alternating regions of a quantum dot active region and a strain-compensation region, and a cap layer. The strain-compensation region is formed to eliminate the compressive strain of an adjacent quantum dot active region, thus allowing quantum dot active regions to be densely-stacked. The densely-stacked quantum dot active region provides increased optical modal gain for semiconductor light emitting devices such as edge emitting lasers, vertical cavity lasers, detectors, micro-cavity emitters, optical amplifiers or modulators.

NERS-active structures for use in Raman spectroscopy include protrusions extending from a surface of a substrate. A Raman signal-enhancing material is disposed on at least one surface of a first protrusion and at least one surface of a second protrusion. The Raman signal-enhancing material disposed on the first protrusion projects laterally in a direction generally towards the second protrusion, and the Raman signal-enhancing material disposed on the second protrusion projects laterally in a direction generally towards the first protrusion. At least a portion of the Raman signal-enhancing projecting from the first protrusion and at least a portion of the Raman signal-enhancing material projecting from the second protrusion may be separated by a distance of less than about 10 nanometers. Raman spectroscopy systems include such NERS-active structures, and methods for performing Raman spectroscopy include irradiating an analyte proximate such a NERS-active structure and detecting Raman-scattered radiation scattered by the analyte.