Abstract: An optical spectrometer for combustion flame temperature determination includes at least two photodetectors positioned for receiving light from a combustion flame, each of the at least two photodetectors having a different, overlapping bandwidth for detecting a respective output signal in an ultraviolet emission band; and a computer for subtracting a respective output signal of a first one of the at least two photodetectors from a respective output signal of a second one of the at least two photodetectors to obtain a segment signal, and using the segment signal to determine the combustion flame temperature.

Abstract: A detection system for detecting gamma rays including a scintillator crystal for receiving at least one gamma ray and generating at least one ultraviolet ray and an avalanche photodiode for detecting the ultraviolet ray. The avalanche photodiode includes: a substrate having a first dopant; a first layer having a second dopant, positioned on top of the substrate; a passivation layer for providing electrical passivation on a surface of the avalanche photodiode; a phosphorous silicate glass layer for limiting mobile ion transport, positioned above of the first layer; and a pair of metal electrodes for providing an ohmic contact wherein a first electrode is positioned below the substrate and a second electrode is positioned above the first layer. The avalanche photodiode comprises a first sidewall and a second sidewall forming a sloped mesa shape.

Abstract: An aspect of the present invention is directed to an avalanche photodiode (APD) device for use in oil well drilling applications in harsh, down-hole environments where shock levels are near 250 gravitational acceleration (G) and/or temperatures approach or exceed 150° C. Another aspect of the present invention is directed to an APD device fabricated using SiC materials. Another aspect of the present invention is directed to an APD device fabricated using GaN materials.

Abstract: A flame sensor for combustion flame temperature determination comprises elongated extensions that are positioned with parallel interdigitated longitudinal axis with respect to one another. An optical spectrometer comprises the sensor and a system comprises the sensor. A method for combustion flame temperature determination comprises obtaining a first photodiode signal and a second photodiode signal by using photodiode devices comprising photodiodes with elongated extending interdigitated digits. A method of fabricating a flame sensor for combustion flame temperature determination, comprises forming first and second photodiodes with elongated extending interdigitated digits.

Abstract: A radiation detector includes: a scintillator which produces UV photons in response to receiving radiation from a radiation producing source; and, a wide bandgap semiconductor device sensitive to the UV photons produced by the scintillator. The semiconductor device produces an electric signal as a function of the amount of UV photons incident thereon. Preferably, the electric signal is then measure, recorded and/or otherwise analyzed.

Abstract: An aspect of the present invention is directed to an avalanche photodiode (APD) device for use in oil well drilling applications in harsh, down-hole environments where shock levels are near 250 gravitational acceleration (G) and/or temperatures approach or exceed 150° C. Another aspect of the present invention is directed to an APD device fabricated using SiC materials. Another aspect of the present invention is directed to an APD device fabricated using GaN materials.

Abstract: An optical spectrometer for combustion flame temperature determination includes at least two photodetectors positioned for receiving light from a combustion flame, each of the at least two photodetectors having a different, overlap ping bandwidth for detecting a respective output signal in an ultraviolet emission band; and a computer for subtracting a respective output signal of a first one of the at least two photodetectors from a respective output signal of a second one of the at least two photodetectors to obtain a segment signal, and using the segment signal to determine the combustion flame temperature.

Abstract: A flame sensor for combustion flame temperature determination, comprising a first photodiode formed with elongated extending digits, and having a range of optical responsivity within an OH band for producing a first output signal; and a second photodiode formed with for receiving light from a combustion flame and having a range of optical responsivity in a different and overlapping portion of the OH band than the first photodiode device OH band for producing a second output signal; wherein the elongated extensions are positioned with parallel interdigitated longitudinal axis with respect to one another. An optical spectrometer comprises the sensor and a system comprises the sensor.

Abstract: A detector includes a filter for substantially blocking photons having wavelengths greater than about 250 nm. A photodiode has a low dark current less than about 0.4 pA/cm2. A current from the photodiode is proportional to a quantity of photons having wavelengths less than or equal to about 250 nm which pass through the filter and impinge the photodiode. A processor determines the quantity of photons impinging the photodiode as a function of the current. In a preferred embodiment, the photodiode is a SiC photodiode.

Abstract: A radiation detector includes: a scintillator which produces UV photons in response to receiving radiation from a radiation producing source; and, a wide bandgap semiconductor device sensitive to the UV photons produced by the scintillator. The semiconductor device produces an electric signal as a function of the amount of UV photons incident thereon. Preferably, the electric signal is then measure, recorded and/or otherwise analyzed.

Abstract: An optical sensor system includes a housing having an open end; first and second windows situated in the housing; a fastener for situating the first window closer to the open end than the second window and permitting an air exchange between a sensing region and the second window; a hermetic seal between the second window and the housing; and an optical sensor situated between the second window and a wall of the housing such that the air exchange does not occur inside the optical sensor. The first and second windows can include materials selected from the group consisting of sapphire, quartz, and glass; the optical sensor to be protected can include silicon carbide; and the sensing region can include a combustion region.

Abstract: A photocurrent detector circuit includes a photodiode coupled to an input terminal of a first operational amplifier. A first resistor has a first end coupled to the photodiode and a second end coupled to an output terminal of the first operational amplifier. A first diode has a first end coupled to the photodiode. A second resistor has a first end coupled to a second end of the first diode. A low gain bias network is coupled between a second end of the second resistor and the output terminal of the first operational amplifier. A second diode has a first end coupled to the photodiode. A clamp bias network is coupled between a second end of the second diode and the output terminal of the first operational amplifier. Preferably, the photodiode and the first and second diodes include silicon carbide. The detector may further include second and third operational amplifiers coupled to the output terminal of the first operational amplifier.

Abstract: Intensity of optical emission from a combustion flame within a gas turbine combustor is monitored through an optical window in the combustor wall by a primary detector. Because the window is susceptible to becoming coated with deposits during combustor operation, compensation for presence of a coating is achieved by directing illumination from an optical signal source, such as a silicon carbide light-emitting diode, into the window for internal reflection at an optical interface defined by the combustion side surface. A compensation detector, such as a silicon carbide photodiode, detects intensity of the internally reflected illumination as an indicator of the window coating thickness. The compensation detector is located at a non-combustion side of the window, along with a reference detector that responds to intensity of optical signal source illumination reflected from the non-combustion side surface of the window.

Abstract: An optical radiation detector, such as a silicon carbide photodiode ultraviolet radiation detector, is employed for real time, noninvasive monitoring and diagnosis of combustion dynamics in gas turbine engines. The SiC photodiode responds to flame ultraviolet emission, and a Fast Fourier Transform spectrum analyzer peak acoustic frequency components of the detector signal as indicators of systematic gas pressure vibrations related to combustion. The combustion may be modified in accordance with the monitored acoustic frequency components.

Abstract: A MOSFET includes a first SiC semiconductor contact layer, a SiC semiconductor channel layer supported by the first SiC contact layer, and a second SiC semiconductor contact layer supported by the channel layer. The second contact and channel layers are patterned to form a plurality of gate region grooves therethrough. Each of the gate region grooves includes a base surface and side surfaces which are covered with groove oxide material. A plurality of metal gate layers are provided, each being supported in a respective one of the plurality of grooves. A plurality of deposited oxide layers are provided, each in a respective one of the grooves so as to be supported by a respective one of the plurality of metal gate layers. A first metal contact layer is applied to the surface of the first SiC contact layer, and a second metal contact layer is applied to a portion of the surface of the second SiC contact layer.

Abstract: A silicon carbide (SiC) junction field effect transistor (JFET) device is fabricated upon a substrate layer, such as a p type conductivity SiC substrate, using ion implantation for the source and drain areas. A SiC p type conductivity layer is epitaxially grown on the substrate. A SiC n type conductivity layer is formed by ion implantation or epitaxial deposition upon the p type layer. The contacting surfaces of the p and n type layers form a junction. A p+ type gate area supported by the n type layer is formed either by the process of ion implantation or the process of depositing and patterning a second p type layer. The source and drain areas are heavily doped to n+ type conductivity by implanting donor ions in the n type layer.

Abstract: Combustion in a gas turbine is controlled through use of flame spectroscopy in order to achieve low NO.sub.x emissions in the exhaust. By detecting and monitoring the combustion flame in the turbine to determine intensity of ultraviolet spectral lines, and dynamically adjusting the fuel/air ratio of the fuel mixture such that this intensity remains below a predetermined level associated with a desired low level of NO.sub.x emissions, the engine produces significantly reduced NO.sub.x emissions in its exhaust but at a sufficiently high combustion flame temperature to avoid any undue risk of flame-out, thereby assuring stable, safe and reliable operation.

Abstract: Combustion in a boiler burner is controlled through use of flame spectroscopy in order to achieve low NO.sub.x emissions in the exhaust. By monitoring the combustion flame in the boiler burner to determine intensity of ultraviolet spectral lines, and dynamically adjusting the fuel/air ratio of the fuel mixture such that this intensity remains below a predetermined level associated with a desired low level of NO.sub.x emissions, the boiler burner produces significantly reduced NO.sub.x emissions in its exhaust but at a sufficiently high combustion flame temperature to avoid any undue risk of flame-out, thereby assuring stable, safe and reliable operation.

Abstract: Respective SiC (silicon carbide) photodiode sensors are used to measure flame temperature at each cylinder of an internal combustion engine, and information generated by the SiC photodiode sensors is used to control the fuel injection in a feedback loop to control individual cylinder flame temperature and combustion.

Abstract: A silicon carbide photodiode exhibiting high short-wavelength sensitivity, particularly in the ultraviolet spectrum, and very low reverse leakage current includes a p type conductivity 6H crystalline substrate. A first p- silicon carbide crystalline layer is epitaxially grown on the body. A second n+ silicon carbide crystalline layer is epitaxially grown on the first layer and forms a p-/n+ junction with the first layer. A metallic upper contact layer is formed on a predetermined surface region of the second layer oppositely situated from the junction. The second layer is of a uniform minimum thickness, generally less than 1000 Angstroms, with a greater thickness, typically 3000-4000 Angstroms, beneath the predetermined surface region. The thicker portion of the second layer occupies less than 10% and generally less than 1% of the total second layer surface area.