Abstract: A piezoresistor having a base substrate with a quantum well structure formed on the base substrate. The quantum well structure includes at least one quantum well layer bounded by barrier layers. The barrier layers are formed from a material having a larger bandgap than the at least one quantum well layer.

Abstract: An electrical contact for a silicon carbide component comprises a material that is in thermodynamic equilibrium with silicon carbide. The electrical contact is typically formed of Ti3SiC2 that is deposited on the silicon carbide component.

Abstract: A high-temperature balance includes a piezoelectric material, such as langasite, that is stable at high temperatures. The frequency response of the balance is monitored to determine the change in mass of material deposited on the balance in a high-temperature environment. Accordingly, the balance can be used to monitor high-temperature deposition rates or to perform thermogravimetric analysis. The high-temperature balance of this invention can further be operated as a nanobalance to measure monolayer changes in film thickness.

Abstract: A piezoresistor having a base substrate with a quantum well structure formed on the base substrate. The quantum well structure includes at least one quantum well layer bounded by barrier layers. The barrier layers are formed from a material having a larger bandgap than the at least one quantum well layer.

Abstract: An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

Abstract: A method of electrochemical machining of micromechanical structures from a silicon substrate having both p and n-type regions in hydrofluoric electrolyte solution is disclosed. Only the p-type region of the silicon substrate may be selectively etched by providing means for inhibiting the injection of holes from the p-type region through the n-type region. Inhibiting the injection of holes includes forming a p-type layer over the n-type region, forming a layer of material inert to the electrochemical etchant over the n-type region, imposing a reverse electrical bias between the p-type region and n-type region, and providing recombination centers in the n-type region to induce recombination of holes injected into the n-type region.

Abstract: An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

Abstract: A method of photo-assisted electrochemical machining of micromechanical structures from a silicon substrate having both p and n regions in a hydrofluoric electrolyte solution is disclosed. Both p and n regions of the silicon substrate may be selectively etched, with differing regions as etch stops, at controlled rates by the appropriate choice of cell bias, p-n junction bias and illumination intensity.

Abstract: The sensor includes a sensing element of a copper oxide ceramic with perovskite related structures. Electrical circuitry responsive to the conductivity of the sensing element is provided. This conductivity is a function of the gas partial pressure. A preferred ceramic oxide is in the Y-Ba-Cu-O system and these compounds exhibit a markedly greater dependence of conductivity on oxygen partial pressure than materials previously used.

Abstract: A ceria electrolyte composition is disclosed. The composition provides high ionic conductivity and low electronic conductivity under reducing conditions. Fuel cells employing the disclosed composition exhibit improved efficiency and power density.

Abstract: The resistor includes a cooper oxide ceramic with perovskite related structures exhibiting positive temperature coefficient of resistance characteristics in the temperature range of 300.degree.-900.degree. C. Suitable materials are YBa.sub.2 Cu.sub.3 O.sub.7-x, La.sub.2 CuO.sub.4 and related compounds with other rare earth elements substituted for Y and La and other alkaline earth elements substituted for Ba.