Mid-IR LEDs Suggest Scene-Generation Applications

Scientists at the US Army Research Laboratory in Adelphi, working with Maxion Technology of Hyattsville, both in Maryland, have reported wall-plug efficiencies of up to 2.8 percent from 3.8-µm interband cascade LEDs at 77 K. The emitters have potential applications in the generation of simulated infrared environments for tests that incorporate military hardware, as well as in the development of IR countermeasures and of chemical and biological sensors.

In the work, the investigators compared the performance of type-II devices that featured various numbers of active/injection layers and square mesa sizes and that varied in postgrowth processing. They found that thinning the substrate improved output intensity by up to six times, and that the incorporation of a surface grating in the design boosted output by at least another 10 percent.