DYNAMIC REFLECTANCE ANISOTROPY AND REFLECTANCE MEASUREMENTS OF THE DEPOSITION OF SI ON GAAS(001)-C(4X4)

Dynamic reflectance anisotropy and reflectance data recorded using a p hoton energy of 1.96 eV is presented for the deposition of atomic Si o n singular GaAs(001)-c(4 x 4) surfaces under molecular beam epitaxy co nditions at 400, 450 and 500 degrees C. Changes in reflectance anisotr opy were detected at the 0.1% of a monolayer level underlining the sen sitivity of the method. Dynamic changes were found in the reflectance anisotropy response upon the interruption of dosing providing a caveat that static reflectance difference spectroscopy does not provide true dynamical information on the surface processes and that temporal info rmation on surface migration is available. Evidence for dramatic chang es in reflectance was found during deposition, these changes being par ticularly pronounced at higher temperatures and are an indicator of su rface roughening processes. Subsequent growth of GaAs returns the surf ace to GaAs like behaviour after similar to 15 monolayers and provides real time evidence for Si segregation at the surface.