Two-color luminescence from a single type-II InAsSbP/InAs heterostructure

Gradient scanning Kelvin-probe microscopy has been for the first time used to study $p$–$n$ hetero-junctions based on narrow-gap compounds in the In-As-Sb-P solid-solution system. Redistribution of the flow of injected carriers in the sample along the direction of the external electric field is demonstrated for the example of a single type-II $p$-InAsSbP/$n$-InAs heterostructure. When a forward bias is applied to the hetero-structure, two-band luminescence is observed, i.e., that of the interface type at the $p$-InAsSbP/$p$-InAs heterointerface and of the bulk type in indium arsenide. It is shown that indirect (interface) transitions exhibit a higher radiative-recombination efficiency than direct interband transitions. The observation of multiband electroluminescence spectra opens up a means of developing single-heterostructure multicolored light-emitting diodes for the mid-IR spectral range (3–5 $\mu$m).