Cascaded Superlattice InAs/GaSb Light-Emitting Diodes for Operation in the Long-Wave Infrared

Superlattice InAs/GaSb light-emitting diodes with peak emission wavelength of 8.6 μm and output power approaching 190 μW at 77 K from a 120 × 120 μm
²
mesa are demonstrated. Output power in excess of 600 μ.W was demonstrated from a 520 × 520 μm mesa at 1 A drive current and 50% duty cycle. Devices were grown by molecular beam epitaxy on lightly n-doped GaSb substrates and employed a 16-stage cascaded active region configuration to improve current efficiency and increase optical output. Emitting regions were coupled by semi-metallic tunnel junctions consisting of a p-GaSb layer and a thickness-graded InAs/GaSb superlattice stack.