Observation of reflection high energy electron diffraction intensity oscillations during Si molecular beam epitaxial growth from disilane

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Abstract
Reflection high energy electron diffraction (RHEED) intensity oscillations have been used to monitor the growth of Si(001) during gas source molecular beam epitaxy (Si-GSMBE) from disilane. Oscillations are easily obtained on well-prepared surfaces on which a buffer layer has been grown. Oscillations of the specular beam in the [010] azimuth have been measured as a function of temperature and disilane flow rate. Strong and damped oscillations were observed between 610 and 680 °C in the two-dimensional growth regime. At higher temperatures, growth by step propagation dominated, while at lower temperatures growth became three-dimensional (3D) and consequently oscillations were weak or absent. Growth rates, as determined from the oscillations, are found to be independent of incident beam flux at substrate temperatures below 600 °C, but become dependent at higher temperatures. An Arrhenius plot indicates an activation energy (EA) of 40.7 kcal/mol in the low-temperature regime (T<600 °C) and an apparent EA dependence on disilane flux in the high-temperature regime.