Micro-Raman study of InAs/GaSb superlattices from front and cleaved edge

The InAs/GaSb superlattice (SL) has a ``broken-gap'' type II band alignment, with its effective bandgap being able to be tuned by changing the thickness of individual layers. Therefore, it is of great interest for mid- and far-IR detection. Because the SL does not have common cation or anion at the interface, there are two types of interfacial layers: InSb and GaAs, that impact the device performance. We investigate the SLs grown on either GaSb or InAs substrate and with difference interfacial treatment using confocal micro-Raman spectroscopy on both front surface and cleaved edge of the epilayer with polarization.