Defect levels in InAs/InAsSb type-II superlattice for LWIR cascade detectors

This work presents DLTS (deep level transient spectroscopy) and PL (photoluminescence) results for a longwave infrared (LWIR) type-II InAs/InAsSb superlattice (T2SLs) based cascade detectors grown by a RIBER Compact 21-DZ solid source molecular beam epitaxy (MBE) system on GaAs substrate. The absorber was optimized for 10.6 μm at 300 K. In order to verify defects from individual heterostructure layers, DLTS measurements were performed for the entire cascade structure and a single cell (stage) of the cascade detector. The obtained results indicate that there are three defect levels (NDPs- native point defects) located in the absorber layer and one related to the occurrence of mismatch dislocations between buffer and substrate.