Surface segregation of indium atoms during molecular beam epitaxy of InGaAs/GaAs superlattices on (n11)A GaAs substrates

We have investigated substrate off-angle dependence of surface segregation of In atoms during molecular beam epitaxy (MBE) of pseudomorphic In0.08Ga0.92As/GaAs superlattices (SLs) on (n11)A-oriented GaAs substrates (n=3-5). Surface segregation length of the In atoms (λ: 1/e decay length of the In content profile along the growth direction) was characterized by high resolution X-ray diffraction (HRXRD) and low-temperature (11 K) photoluminescence (PL) measurements. λ obtained for the (n11)A SLs were 1.2-1.4 times longer than that (λ=1.57nm) for the simultaneously grown (1 0 0) SL, and the (4 1 1)A SL showed the longest λ of 2.16 nm. The obtained substrate off-angle dependence of the In segregation length is quite similar to the incorporation life-time (τc) of Ga adatoms reported for MBE growth of GaAs on channeled (1 0 0) substrates, indicating that larger surface migration of Ga adatoms during MBE growth on (n11)A substrates causes enhanced surface segregation of In atoms in the (n11)A InGaAs system.