Abstract: A combustible gas sensor diode including a SiC semiconductor substrate, on top of which an AlN layer and a catalytic metal “gate” electrode are deposited is disclosed. The combustible gas sensor diode can be operated in either a D.C. forward conduction mode or an A.C. reverse bias mode. Methods of detecting combustibles in both D.C. and A.C. modes are further disclosed.

Abstract: A combustible gas sensor diode including a SiC semiconductor substrate, on top of which an AlN layer and a catalytic metal “gate” electrode are deposited is disclosed. The combustible gas sensor diode can be operated in either a D.C. forward conduction mode or an A.C. reverse bias mode. Methods of detecting combustibles in both D.C. and A.C. modes are further disclosed.

Abstract: A substrate covered with an insulating layer and a catalytic gate electrode 26 disposed on the insulating layer. The catalytic gate electrode 26 has a first end having a first contact pad 30 and a second end having a second contact pad 32. A meander 28 is placed between the first contact and the second contact. A third contact pad 24 is coupled to the underside of the substrate 22. The temperature is measured between the first contact pad 30 and second contact pad 32 while sensor's response to gas concentration is sensed between the gate electrode 26 and the third contact 24.

Abstract: A combustible gas sensor diode including a SiC semiconductor substrate, on top of which an AlN layer and a catalytic metal “gate” electrode are deposited is disclosed. The combustible gas sensor diode can be operated in either a D.C. forward conduction mode or an A.C. reverse bias mode. Methods of detecting combustibles in both D.C. and A.C. modes are further disclosed.

Abstract: A combustible gas sensor diode including a SiC semiconductor substrate, on top of which an AlN layer and a catalytic metal “gate” electrode are deposited is disclosed. The combustible gas sensor diode can be operated in either a D.C. forward conduction mode or an A.C. reverse bias mode. Methods of detecting combustibles in both D.C. and A.C. modes are further disclosed.

Abstract: A combustible gas sensor diode including a SiC semiconductor substrate, on top of which an AlN layer and a catalytic metal “gate” electrode are deposited is disclosed. The combustible gas sensor diode can be operated in either a D.C. forward conduction mode or an A.C. reverse bias mode. Methods of detecting combustibles in both D.C. and A.C. modes are further disclosed.

Abstract: A method for depositing a metal film onto the semiconductor substrate and insulator of a MOS sensor is provided. The method utilizes a laser ablation technique to deposit metal films having a desired thickness and roughness to enhance the reliability and sensitivity of a MOS sensor to combustible gases.

Abstract: A crystalline silicon carbide film is grown on a heated crystalline silicon substrate by laser ablation of a pure carbon target. For substrate temperatures during deposition above 1000.degree. C. and single crystal silicon substrates the resulting SiC film is expitaxially oriented with respect to the substrate. Films of stoichiometric SiC are grown up to thicknesses of about 4000.ANG.. These films grow on top of the silicon substrate and whereas the source of carbon for the film is from the ablation plume of the carbon target the source of the silicon is from the substrate. By using a method of alternate ablation of a pure carbon and a pure silicon target, similar epitaxial films can be grown to thicknesses in excess of 1 .mu.m with part of the silicon being supplied by the ablation plume of the silicon target.

Abstract: A system for maintaining engine air/fuel operation within the efficiency window of a catalytic converter. Fuel delivered to the engine is adjusted in response to a step change in an output of an exhaust gas oxygen sensor positioned upstream of the converter. The step change is shifted in response to an error signal derived from a downstream emissions sensor.

Abstract: A control system for maintaining engine air/fuel operation within the efficiency window of a catalytic converter. An exhaust gas oxygen sensor having a step change between first and second output states and positioned downstream of the converter. A step change in the downstream sensor output is initialized to an initial air/fuel ratio by pumping current through one of the sensing electrodes of the downstream sensor. An emission control signal is derived from the initialized downstream sensor output to bias an air/fuel feedback loop.

Abstract: A method of operating a selective combustible sensor having a pump cell and a sensor cell includes the steps of immersing the sensor in a gaseous atmosphere having at least two combustible gases and oxygen gas and allowing the gaseous atmosphere to enter a region between the pump cell and the sensor cell, applying a pumping current to the pump cell, sensing an e.m.f. (V.sub.s), across the sensor cell, varying at least either the V.sub.s or temperature to make the sensor insensitive to one of the combustible gases, and detecting the other combustible gases present in the gaseous atmosphere.