Mid-Infrared Light-Emitting Diodes and Photodiodes for Hydrocarbon Sensing

The properties of light-emitting diodes (LEDs) and photodetectors have been investigated to establish their suitability for methane sensing. Using these components it is possible to achieve good signal-to-noise values at both the char- acteristic absorption wavelength and also at , an attractive wavelength for use as a reference channel. A limit of sensitivity of approximately 400 ppm, with an integration time of 10 s and a path length of 5 cm, was estimated for methane detection Index Terms—Gas detectors, infrared detectors, light-emitting diodes (LEDs), semiconductor devices.