Kinetics and dynamics of Si GSMBE studied by reflectance anisotropy spectroscopy

Abstract

Kinetic and dynamic information from semiconductor surfaces is of great importance in the understanding of growth processes in molecular beam epitaxy. Surface related information, such as coverage and composition, is often measured with techniques such as temperature programmed desorption under conditions away from those encountered in a realistic growth environment. If the adsorbate/precursor has a strong influence on the electronic structure of the surface it is possible to make in situ and more direct measurements using optical techniques. Reflectance anisotropy spectroscopy (RAS) has been shown to be sensitive to morphological, structural and chemical changes on the surface and is well-suited for this role. Structural changes on the Si(001) surface resulting from epitaxial growth were shown to be the origin of RA oscillations observed during layer by layer growth. Hydrogen produced on the surface from the decomposition of hydride precursors is very important in the growth of Si and SiGe, since it can prevent further adsorption of hydrides through site blocking, behave as a surfactant and change the spectroscopic RA response. We can use the single reconstruction domain produced on vicinal Si(001) surfaces to explore surface-hydride–hydrogen interactions. We have made isothermal measurements during adsorption and desorption cycles and compared the results with various models whose validity under the condition studied is discussed.