LOCAL ARRANGEMENT OF SILYLENE GROUPS ON SI(100)2X1 AFTER SIH4 DECOMPOSITION

The interaction between Si(100)2 x 1 and SiH4 under UHV chemical vapor deposition conditions between 550 and 690 K is studied with high-reso lution scanning tunneling microscopy and kinetic model calculations. I n addition to small anisotropic Si islands and patches of hydrogen-ter minated substrate, metastable cross-shaped structural tetramer units a re formed in this temperature region. These tetramers are interpreted as a combination of four SiH2 groups connecting four Si substrate atom s, and their coverage is correlated with the decomposition kinetics of SiH2.