Efficient and cost-effective light sources operating in the mid-infrared are in demand for sensing applications within the environmental, agricultural, medical, industrial and defence sectors. Inter-band cascade light-emitting diodes (IC-LEDs) based on InAs/GaSb superlattices (SLs) have shown promise via high wall-plug efficiency and low turn-on voltage at room temperature. Competing technologies suffer from a variety of performance and growth limitations motivating investigation of the optoelectronic properties of these prototypical IC-LEDs.
We have developed an efficient computational framework allowing for predictive calculations of SL optoelectronic properties. This framework is employed to explicitly compute the radiative recombination coefficient B, where B is used to quantify radiative performance. For a structure with equal InAs and GaSb layer thicknesses we quantify the impact of the structural and underlying bulk material properties. We observe high B values that are competitive with quantum well technologies. This, combined with expected low non-radiative losses in these types of structures, corroborates the observed high output power in InAs/GaSb SL IC-LEDs.
After quantifying the factors impacting B in an equal layer thickness InAs/GaSb SL, we performed high-throughput calculations to maximise B at room temperature across the mid-infrared wavelength range. This analysis quantifies the key role played by the relative thickness of the InAs and GaSb layers in determining B at fixed wavelength. Our analysis provides guidance for the growth of optimised InAs/GaSb SLs for mid-infrared light emitters via structural optimisation.
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