Increase in midwave infrared light emitting diode light output due to substrate thinning and texturing

Abstract

Midwave infrared (MWIR) light sources with high optical power are required for many applications. The authors report here the MWIR (3.8μm peak) light emission from an interband cascade light emitting diode (LED) structure with 18 cascaded active/injection regions grown on GaSb substrate. The light emission is observed from the substrate side of the device. An increase of six times of light output power is observed due to substrate thinning and another 50% increase is observed due to texturing the emission surface. The authors observed 400μW emission power for room temperature operation with 15mA LED injection current. Experiments were carried out with different grating patterns and etch depths. The device with a 2μm square grating and a 1μm etch depth has the highest optical emission power.