KINETICS AND DYNAMICS OF SI GSMBE STUDIED BY REFLECTANCE ANISOTROPY SPECTROSCOPY

Kinetic and dynamic information from semiconductor surfaces is of grea t importance in the understanding of growth processes in molecular bea m epitaxy. Surface related information, such as coverage and compositi on, is often measured with techniques such as temperature programmed d esorption 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 s itu and more direct measurements using optical techniques. Reflectance anisotropy spectroscopy (RAS) has been shown to be sensitive to morph ological structural and chemical changes on the surface and is well-su ited for this role. Structural changes on the Si(001) surface resultin g from epitaxial growth were shown to be the origin of RA oscillations observed during layer by layer growth. Hydrogen produced on the surfa ce from the decomposition of hydride precursors is very important in t he growth of Si and SiGe, since it can prevent further adsorption of h ydrides through site blocking, behave as a surfactant and change the s pectroscopic RA response. We can use the single reconstruction domain produced on vicinal Si(001) surfaces to explore surface-hydride-hydrog en interactions. We have made isothermal measurements during adsorptio n and desorption cycles and compared the results with various models w hose validity under the condition studied is discussed. (C) 1998 Elsev ier Science B.V. All rights reserved.