Heterostructures like $\mathrm{InAs}\text{/}\mathrm{GaSb}$ superlattices (SLs) are distinctly different from well-studied ones like $\mathrm{GaAs}\text{/}\mathrm{AlAs}$ SLs in terms of band alignment, common interface atom, and phonon spectrum overlapping of the constituents, which manifests as stark differences in their electronic and vibrational properties. This paper reports a comprehensive examination of all four types of phonon modes (confined, quasiconfined, extended, and interface) that have long been predicted for the $\mathrm{InAs}\text{/}\mathrm{GaSb}$ SL, with the observation and interpretation of a set of phonon modes by performing cleaved edge $\mu$-Raman study with polarization analysis. Furthermore, we show a signature of symmetry reduction from ${\mathrm{D}}_{2\mathrm{d}}$ for $\mathrm{GaAs}\text{/}\mathrm{AlAs}$ SL to ${\mathrm{C}}_{2\mathrm{v}}$ for InAs/GaSb SL revealed as a phonon-polariton effect.

• Received 1 February 2015

DOI:https://doi.org/10.1103/PhysRevB.91.235317