Gas source molecular beam epitaxy and X-ray absorption fine structure characterization of InGaAs/InP short period superlattices

Abstract

InGaAs/InP short period superlattices (SPSLs) were grown using gas source migration enhanced epitaxy (GSMEE) and using gas source molecular beam epitaxy (GSMBE) on (001)InP substrates. The local structure around the interfaces was investigated by Ga K-edge X-ray absorption fine structure (XAFS) using synchrotron radiation (SR). It was confirmed by the observation of persistent reflection high-energy electron diffraction (RHEED) oscillations that layer-by-layer nucleation takes place even during the growth of the heterointerfaces by precise control of migration enhanced epitaxy (MEE) sequences. XAFS analysis showed that the first nearest neighbor around Ga in the GSMEE grown sample with In-As interfaces is As, while those in the GSMBE grown sample are As and P. These results suggest that the atomically-controlled abrupt heterointerfaces can be obtained by GSMEE, whereas some intermixing of atoms at the heterointerfaces takes place in samples grown by GSMBE.