A REFLECTION HIGH-ENERGY ELECTRON DIFFRACTION-REFLECTANCE ANISOTROPY SPECTROSCOPY STUDY OF SILICON GROWTH DYNAMICS DURING GAS-SOURCE MOLECULAR-BEAM EPITAXY FROM SILANES

Molecular beam epitaxy (MBE) provides an ideal experimental vehicle fo r the in situ study of thin film growth dynamics. By using a combinati on of reflection high energy electron diffraction (RHEED) and reflecta nce anisotropy (difference) spectroscopy [RA(D)S], it is possible to s eparate morphological (long range order) and local electronic structur e effects, which we demonstrate with the growth of silicon films from disilane (Si2H6) on Si(001) (2 x 1) + (1 x 2) reconstructed surfaces. The rate-limiting step in Si growth from both monosilane (SiH4) and di silane is the desorption of molecular hydrogen and we have found using RAS that, over a significant range of temperature and coverage, hydro gen desorption follows zeroth order kinetics as the result of a step-m ediated process. Finally, we show how this influences the growth rate on substrates of differing degrees of vicinality.