Strain analysis of compositionally tailored interfaces in InAs/GaSb superlattices

The effect of interface composition control on interfacial strain distribution in InAs/GaSb superlattices on (100)-GaSb substrates is investigated by atomic resolution scanning transmission electron microscopy. The interface composition was controlled by either depositing InSb at each interface or soaking the GaSb-on-InAs interface under Sb2 atmosphere. The strain profiles reveal a distinct difference in the extent to which the superlattice strain is balanced using the two methods. In particular, they indicate that the degree of strain balance achievable with soaking is inherently limited by the arsenic surface coverage during GaSb-on-InAs interface formation, emphasizing the influence of V/III flux ratio at this interface. The results also explain observed X-ray diffraction profiles