Investigation of the polarization characteristics of GaInAsSb‐covered inAs quantum dots for application to surface‐emitting devices

Self‐assembled InAs quantum dots are expected to be applied as active layers for long‐wavelength emitting devices used in fiber‐optic communications. A problem with these is the deterioration of emission efficiency accompanying the accumulation of strain from increasing wavelengths to beyond the 1.3‐µm range on GaAs substrates. However, with the application of a GaInAsSb covering layer containing a small quantity of antimony (Sb), as proposed in this research, it will become possible to improve the emission efficiency and to have long‐wavelength emission in the 1.5‐µm band. Meanwhile, in order to use such quantum dots as surface‐emitting devices, the in‐plane polarization characteristics must be clarified. However, the polarization characteristics of quantum dots containing Sb have not been reported before now. In this paper, we focus on the influence on the emission characteristics of the transformation of the dot shape due to the addition of Sb. The polarization characteristics of photoluminescence due to the addition of Sb and of In to the cover layer are measured, the dependency of the polarization degree on the dot structure is evaluated, and guidelines for surface‐emitting‐type device applications are given.