High-power mid-wave infrared LED using W-superlattices and textured surfaces

Efficient mid-infrared light output has been obtained by incorporating a W-superlattice into a cascaded mid-infrared LED structure and by thinning and roughening of the emission side of the structure. At cryogenic temperatures, a radiance of ∼13.4 W/cm2-sr is achieved. Compared to the best published InAs/GaSb mid-IR LED, the maximum radiance is improved by ∼2.0×, while the wallplug efficiency improvement at the maximum radiance is improved >10×. For room temperature measurements on an un-thinned 400 μm diameter diode, the radiance (light output power) for a quasi-continuous wave and 1% duty cycle were ∼ 0.48 W/cm2-sr (2.4 mW) and ∼1.35 W/cm2-sr (6.8 mW), respectively. When compared to previous room temperature 4.2 μm LEDs, at a 1% duty cycle, this LED has optical powers that are 3× brighter. When compared to thermal emitters used in gas sensors, in the quasi-continuous wave, this LED uses ∼100× less energy per measurement.