Investigating the physics of higher-order optical transitions in InAs/GaSb superlattices

We present an optical spectroscopy analysis of the molecular beam epitaxy-grown InAs/GaSb quantum systems to study the higher-order optical transitions in InAs/GaSb superlattices (SLs). We have investigated two type-II SL structures with different layer widths: $\mathrm{In}{\mathrm{As}}_{8\mathrm{ML}}/\mathrm{Ga}{\mathrm{Sb}}_{8\mathrm{ML}}$ and $\mathrm{In}{\mathrm{As}}_{10\mathrm{ML}}/\mathrm{Ga}{\mathrm{Sb}}_{10\mathrm{ML}}$. To experimentally determine the spectral distribution of the higher-order transitions, the Fourier-transformed photoluminescence and Fourier-transformed photomodulated reflectance measurements were used. These measurements were undertaken vs temperature and incident polarization of the probing beam. Complementary theoretical calculations based on the eight $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ formalism were also performed to identify the electron and heavy and light hole energy band ladder. Polarization-dependent measurements indicated the interchanging nature of the light and heavy hole states for the second and third valence band vs the SL wave vector $({k}_z)$ along the growth direction. The results were compared with other calculations based on different models and existing experimental results, then summarized and reviewed for possible numerical parameters application ranges in the interface modeling.