Comparison of IR LED gas sensors with thermal source products

Energy gaps, charge distribution and optical properties of AlxIn1−xSb ternary alloys

“…Note that by increasing the Al concentration, e 1 decreases monotonically. The trend in e 1 versus x is qualitatively similar to that of n. This is an expected result since e 1 is obtained from the expression (11). The behavior of e 1 with respect to x suggests that as one proceeds from InSb (x = 0) to AlSb (x = 1), the ternary alloy of interest (0 < x < 1) becomes progressively a good insulator.…”

“…Besides, AlInSb provides a convenient strain-compensating barrier material for mid-infrared inter band cascade lasers [10] and other antimonide device structures. Mid-infrared light-emitting diodes are the subject of much research and have great potential in such applications as gas sensing and free-space quantum communications [11,12]. Some of the high brightness light-emitting diodes at the wavelengths range k = 3-10 lm that have been recently reported [13], were fabricated from Al x In 1Àx Sb, where the peak emission wavelength can be tailored by varying the Al concentration.…”

A Novel Solid State Non-Dispersive Infrared CO2 Gas Sensor Compatible with Wireless and Portable Deployment

“…Previous work published in 1997 [19], provides a comparison of gas sensor performance using mid-infrared light emitting diodes (LED) with thermal sources. Whilst the work described in [19] demonstrated the clear advantages using the LED light source, problems with early LED devices in relation to power output, temperature stability, lifetime and cost resulted in marginal performance improvements compared to thermal sources.…”

<title>Improved-efficiency positive and negative luminescent light-emitting devices for mid-infrared gas-sensing applications</title>

“…Here broadband sources are utilised and the integrated absorption over an entire manifold of gas absorption lines used to determine gas concentration. 5 Mid-JR light emitting diodes (LED's) have been considered as alternatives to currently employed incandescent sources because they offer increased efficiency, reliability, are more robust and intrinsically safe, can be modulated at high frequencies, offer longer lifetimes and may not require "burn-in" before operation. Significant advances have recently been made with device output powers up to 1 mW 6,7 at shorter wavelengths (X=4.2-4.6 tm).…”