X-RAY-ABSORPTION FINE-STRUCTURE STUDIES OF SULFUR INTERLAYERS IN MOLECULAR-BEAM EPITAXY-GROWN SRF2/S/GAAS(111)

The interfacial structure between SrF2 epitaxial overlayers and sulfur-passivated GaAs(111)A and B surfaces has been investigated by S K-edge X-ray absorption fine structure (XAFS) measurements using synchrotron radiation soft X-rays. Significant differences between the SrF2/S/GaAs(111)A and SrF2/S/GaAs(111)B systems were found with respect to the existence of S atoms at the interfaces by comparing Xray absorption near edge structure (XANES) spectra and extended X-ray absorption fine structure (EXAFS) analysis results before and after growing the SrF2 epitaxial overlayers on sulfur-passivated surfaces by molecular beam epitaxy.