The characterization of the growth of sub-monolayer coverages ( [formula omitted] to 1 monolayer) of Si and Be on GaAs(001): A reflectance anisotropy spectroscopy and reflection high-energy electron diffraction study

Abstract

The techniques of reflectance anisotropy spectroscopy (RAS) and reflection high-energy electron diffraction (RHEED) have been employed, for the first time in concert, to characterize the growth of sub-monolayer coverages of both Si and Be deposited onto the GaAs(001)- c(4 × 4) surface. The RHEED observations enabled the RAS spectra collected for a series of Si and Be coverages, in the range 0.005 to 1.000 monolayer (ML), to be interpreted in terms of changes in the sample surface structure. For the case of Si/GaAs(001) the following series of surface reconstructions were observed with increasing Si coverage: c(4 × 4), c(4 × 4) (1 × 2) , (1 × 2) , (1 × 2) (3 × 1) and, (3 × 1) . During the deposition of Be GaAs(001) , c(4 × 4), c(4 × 4) (1 × 2) , c(4 × 4) (1 × 3) , (1 × 2) (1 × 3) , (1 × 3) , and (1 × 2) reconstructions were noted to evolve. The fact that unique, but highly reproducible, RAS signatures were obtained for each of these surface phases demonstrates the applicability of a combined RHEED/RAS system for monitoring sub-monolayer heteroepitaxial growth with a surface sensitivity of the order of 1 200th of a monolayer.