High-Power MWIR Cascaded InAs–GaSb Superlattice LEDs

Midwave IR LEDs operating at 3.8 mum with output powers approaching 25 mW at 77 K are reported. Devices based on the InAs-GaSb superlattice material system grown by solid source molecular beam epitaxy are demonstrated in a cascaded active region configuration as high-power IR emitters. Optical and electronic characteristics of 16-stage devices with variable mesa size were examined to assess the performance dependence on device size and injection current. The results are suggestive that output power saturation was due to thermal management limitations and carrier leakage out of the active region. Reported output power measurements were taken without the use of an immersion lens or other collection optics, thus representing the upper hemisphere output. Devices were also demonstrated to generate an upper hemisphere power exceeding 1.4 mW at 220 K under quasi-DC excitation conditions.