MICROSCOPIC PROCESSES IN DEPOSITION-CONCURRENT SURFACE SEGREGATION

During the epitaxial growth process of Fe and Au films on GaAs(001)-4 x 6, we observed various types of deposition-concurrent surface segregations (DCSS). We have investigated the microscopic processes of DCSS using the in situ observation techniques of reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES). The process of DCSS consists of two stages, the initial segregation stage in which deposited atoms react with a substrate to initiate a segregation and the continuous segregation stage which subsequently keeps the segregated atoms atop the film surface without being buried under later deposited atoms. An atomistic model for the continuous segregation stage has been proposed. We have discussed the application of the DCSS phenomenon to surfactant-mediated epitaxy techniques.