Abstract: A photodetector (100, 200, 300) comprising a gallium nitride substrate, at least one active layer (104, 302) disposed on the substrate (102, 202, 306), and a conductive contact structure (106, 210, 308) affixed to the active layer (104, 302) and, in some embodiments, the substrate (102, 202, 306). The invention includes photodetectors (100, 200, 300) having metal-semiconductor-metal structures, P-i-N structures, and Schottky-barrier structures. The active layers (104, 302) may comprise Ga1-x-yAlxInyN1-z-w PzAsw, or, preferably, Ga1-xAlxN. The gallium nitride substrate comprises a single crystal gallium nitride wafer and has a dislocation density of less than about 105 cm?2. A method of making the photodetector (100, 200, 300) is also disclosed.

Abstract: A photodetector comprising a gallium nitride substrate, at least one active layer disposed on the substrate, and a conductive contact structure affixed to the active layer and, in some embodiments, the substrate. The invention includes photodetectors having metal-semiconductor-metal structures, P-i-N structures, and Schottky-barrier structures. The active layers may comprise Ga1−x−yAlxInyN1−z−wPzAsw, or, preferably, Ga1−xAlxN. The gallium nitride substrate comprises a single crystal gallium nitride wafer and has a dislocation density of less than about 105 cm−2. A method of making the photodetector is also disclosed.

Abstract: A solid state optical spectrometer for combustion flame temperature determination comprises: a first photodiode device for obtaining a first photodiode signal, the first photodiode device comprising a silicon carbide photodiode and having a range of optical responsivity within an OH band; a second photodiode device for obtaining a second photodiode signal, the second photodiode device comprising a silicon carbide photodiode and a filter, the second photodiode device having a range of optical responsivity in a different and overlapping portion of the OH band than the first photodiode device; and a computer for obtaining a ratio using the first and second photodiode signals and using the ratio to determine the combustion flame temperature.

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 photodetector comprising a gallium nitride substrate, at least one active layer disposed on the substrate, and a conductive contact structure affixed to the active layer and, in some embodiments, the substrate. The invention includes photodetectors having metal-semiconductor-metal structures, P-i-N structures, and Schottky-barrier structures. The active layers may comprise Ga1-x-yAlxInyN1-z-wPzAsw, or, preferably, Ga1-xAlxN. The gallium nitride substrate comprises a single crystal gallium nitride wafer and has a dislocation density of less than about 105 cm−2. A method of making the photodetector is also disclosed.

Abstract: A solid state optical spectrometer for combustion flame temperature determination comprises: a first photodiode device for obtaining a first photodiode signal, the first photodiode device comprising a silicon carbide photodiode and having a range of optical responsivity within an OH band; a second photodiode device for obtaining a second photodiode signal, the second photodiode device comprising a silicon carbide photodiode and a filter, the second photodiode device having a range of optical responsivity in a different and overlapping portion of the OH band than the first photodiode device; and a computer for obtaining a ratio using the first and second photodiode signals and using the ratio to determine the combustion flame temperature.