Density functional study of the decomposition pathways of SiH3 and GeH3 at the Si(100) and Ge(100) surfaces

By means of first-principles calculations we studied the decomposition pathways of SiH3 on Ge(100) and of GeH3 on Si(100), of interest for the growth of crystalline SiGe alloys and Si/Ge heterostructures by plasma-enhanced chemical vapor deposition. We also investigated H desorption via reaction of two adsorbed SiH2/GeH2 species (beta(2) reaction) or via Eley-Rideal abstraction of surface H atoms from the impinging SiH3 and GeH3 species. The calculated activation energies for the different processes suggest that the rate-limiting step for the growth of Si/Ge systems is still the beta(2) reaction of two SiH2 as in the growth of crystalline Si.