Powerful interface light emitting diodes for methane gas detection

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.