Extremely uniform In 0.08Ga 0.92As/GaAs superlattice grown on a (411)A GaAs substrate by molecular beam epitaxy

Abstract

An In 0.08Ga 0.92As/GaAs strained-layer superlattice (SLS) grown on a (411)A GaAs substrate by molecular beam epitaxy (MBE) was characterized by high resolution X-ray diffraction (HRXRD) and low-temperature photoluminescence (PL) measurements. The (411)A InGaAs/GaAs SLS exhibited much narrower 0th and ±1st HRXRD peaks compared with those of an InGaAs/GaAs SLS simultaneously grown on a (100) GaAs substrate, which is mainly due to the difference of fluctuation of tilting angles of local crystal planes in the SLSs. This fluctuation of the (100) InGaAs/GaAs SLS was caused by a considerable amount of relaxation of lattice-mismatch between InGaAs and GaAs layers. There was no such relaxation in the (411)A InGaAs SLS. Furthermore, a higher PL intensity and a smaller PL linewidth of the (411)A SLS were also observed compared with those of the (100) SLS. These results indicate that the (411)A InGaAs/GaAs SLS has a much improved crystalline quality compared with that of the conventional (100) InGaAs/GaAs SLS.