Powerful interface light emitting diodes for methane gas detection

Abstract

Powerful (light emitting diodes) LEDs which exhibit more than 3.5 mW of output power at room temperature have been fabricated by liquid phase epitaxy (LPE) and characterized. These LEDs are well matched to the CH4 absorption spectrum and confirm the potential of the devices as a key component for use in an infrared CH4 gas sensor. We report on the efficient interface electroluminescence in our LEDs across the InAs/InAsSbP heterojunction consistent with type II emission. This directly suppresses the Auger recombination and enables these sources to emit maximum powers in excess of 3 mW at room temperature. Furthermore, the use of Yb rare earth ion gettering in these devices was found to be effective in increasing the LED output power. We attribute this to a reduction in the residual carrier concentration arising from the removal of unintentional donors and point defects in the InAs active region material. The ring contact geometry was also found to be superior when compared to the dot contacts in our structures. The LEDs demonstrated in this work are sufficiently powerful to be used in a practical methane gas sensor.

Miniature low-power IR monitor for methane detection

“…With the development of the integration technology, detectors, light sources, filters, etc., can be integrated into a miniature optics gas cell, which can further miniaturize the infrared sensor system. This results in a more convenient use of the sensor and decreases possible error introduction by different types of gas cell structures [7,10,12]. Based on this, we have designed the scheme shown in Fig.…”

“…Portable gas detectors for gas leaks are clearly important in a number of these applications, but they must be of a low-cost design for widespread use and availability. The established method for methane gas detection is using a catalytic sensor [5][6][7][8][9], which, however, is not methane specific, and any gas whose ignition is catalyzed by a pellistor will be detected. Additionally, catalytic sensors do not operate correctly in low-oxygen environments and can be poisoned.…”

Tunneling current via dislocations in InAs and InSb infrared photodiodes

“…Despite the fact that InSb and InAs photodiodes are widely used in infrared (IR) technique, improvement of their performance still remains as an important problem [1][2][3][4][5][6][7][8]. An excess dark current frequently observed in these photodiodes at small reverse and forward biases results in decrease of their threshold parameters such as responsivity and specific detectivity.…”

Design of a portable optical sensor for methane gas detection

“…for purging of pipe lines), and (iv) low cost of ownership, since the gas-detection principle is a physical process (not a chemical reaction), and therefore, poisoning of the sensor is not an issue (although dirt/contamination on the optics needs to be considered in the sensor design). For hydrocarbon gases, such as methane, the strongest optical absorption occurs in the mid-IR region, around 3.3 m, but the use of a broadband source in the mid-IR to detect methane [5] has cost and performance limitations. For example, a number of hydrocarbon gases have absorption bands/lines in the same spectral region, so a mid-IR system will often respond to other hydrocarbons, and hence, they are generic hydrocarbon detectors rather than methane-specific.…”