Abstract
Adsorption and thermally-induced dissociation of disilane (Si 2 H 6 ) on clean Ge(001)2 × 1 surfaces have been investigated using a combination of Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS), reflection high-energy electron diffraction (RHEED), and scanning tunneling microscopy (STM). With initial Si 2 H 6 exposure at room temperature, the Si surface coverage increased monotonically, the EELS surface dangling bond peak intensities continuously decreased, and the intensity of half-order RHEED diffraction rods decreased. The low-coverage Si 2 H 6 sticking probability at 300 K on Ge(001) was found to be ∼ 0.5 while the saturation coverage was ∼ 0.5 ML. A new EELS feature, GSH, involving Si-H and Ge-H bond states was observed at Si 2 H 6 exposures φ ≳ 3.4 × 10 13 cm -2 . In contrast to Si 2 H 6 -saturated Si(001), the saturated Ge(001) surface significant fraction of dimerized bonds. Adsorbed overlayers were highly disordered with the primary species on saturated surfaces being SiH 2 , GeH, and undissociated SiH 3 · Si 2 H 6 -saturated Ge(001)2 × 1 substrates were annealed for l min at temperatures T a between 425 and 825 K. Admolecules were mobile at T a = 545 K giving rise to significant ordering in one-dimensional chains. By T a = 605 K, essentially all of the admolecules were captured into coarsened islands. Dangling-bond EELS peaks reappeared by 625 K and the intensities of the half-order RHEED diffraction rods increased. Ge segregation to the surface, which began at T a ≳ 625 K, occurred rapidly at T a ≥ 675 K. All H was desorbed by 725 K. © 1993.