Improvement of InP/InGaAs heterointerfaces grown by gas source molecular beam epitaxy

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Abstract
Surface modification of a P2 beam-exposed InGaAs surface and an As2 beam-exposed InP surface was studied in situ using reflection high energy electron diffraction during gas source molecular beam epitaxy. It is revealed that the InP surface remained stable under As2 beam exposure after forming an InAs surface layer a few monolayers thick; the InGaAs surface became rough by P2 beam exposure. This surface roughening originates from substitutions of As to P atoms around Ga atoms. These substitutions result in the fairly reactive nature of the InGaAs surface under P2 beam exposure. From this viewpoint, we have proposed a new switching sequence which excludes surface gallium atoms by depositing one monolayer of In on the InGaAs surface before P2 beam exposure. This sequence drastically improves heterointerface quality, which was confirmed by an increase in photoluminescence intensity in InGaAs/InP short period superlattices.