Multiple subband transitions and evidence for population inversion in InAs/In(As,Sb) heterostructures

Abstract

We report on improved InAs/InAs1−xSbx heterostructure single quantum well emitters for the mid-infrared wavelength region. An InAlAs barrier layer has been incorporated into the active region of the structures for improved electron confinement. With room temperature pulsed power outputs of 140 μW at a wavelength of 4.3 μm, an improvement of more than a factor of 6 has been achieved compared to similar structures without the barrier layer. Magneto-electroluminescence measurements at 4 K reveal the presence of multiple subband transitions in the spectra. Based on a k⋅p model assuming a type-IIa band offset, these transitions are identified as (e1,hh1) and (e1,lh1). The observation of these multiple transitions is shown to be strong evidence for population inversion in the structures.