EFFECT OF HYDROGEN ON THE GROWTH-KINETICS OF SI(001) DURING GSMBE FROM DISILANE

The effects of hydrogen on the growth kinetics of Si(0 0 1) during gas -source molecular-beam epitaxy from disilane are investigated with kin etic Monte Carlo simulations. The growth model includes the surface de composition of disilane, which requires four mobile and reactive surfa ce species: Si, H, SIH2 and SiH3. Based on recent reflectance anisotro py measurements, the desorption of hydrogen is presumed to occur prefe rentially from step edges. Below approximately 400 degrees C (where th e model allows surface reactions to occur) the accumulation of surface hydrogen is found to prevent growth, but for temperatures above 600 d egrees C, where the surface lifetime of the hydrogen is relatively sho rt, we find no significant differences in the overall growth features in comparison with a solid-source (no hydrogen) growth model of Si(0 0 1). At intermediate temperatures, where surface hydrogen atoms are pr esent but do not prevent growth, we find a higher density of smaller i slands and rougher propagating step edges in comparison with those of the solid-source model. Anisotropic morphological features, which are characteristic signatures in the solid-source model, are suppressed by the surface hydrogen atoms in the gas-source model.