Infrared (3.8μm) interband cascade light-emitting diode array with record high efficiency

Abstract

We report here the light emission from IR interband-cascade (IC) type-II-superlattice light-emitting diode (LED) structures. We employed two different IC epitaxial structures consisting of 9 or 18 periods of active superlattice gain regions separated by multilayer injection regions. The light output (and the voltage drop) of the LEDs is observed to increase as expected with increase in the number of IC active regions. The 18-period LEDs are found to have 0.65% and 2.8% external efficiency at room temperature and liquid nitrogen temperature respectively. An increase of light intensity by 6 times is observed by thinning the GaSb substrates from 500μmto25μm. Another 10% increase is observed using a linear grating on the top surface of the device.