Interaction of phosphine with Si(100) from core-level photoemission and real-time scanning tunneling microscopy

In this paper, we investigate the interaction of phosphine (PH3) on the Si( 100)-2 x 1 surface at temperatures between 635 and 900 K. The hydrogen deso rption, growth mode, surface morphology, and chemical composition and order ing of the surface layer are examined by synchrotron radiation core-level p hotoemission and real-time high-temperature scanning tunneling microscopy. The P 2p core-level spectra indicate that decomposition of PHn is complete above similar to 550 K and the maximum P coverage is strongly influenced by the growth temperature, which governs the coverage of H-terminated sites. The scanning tunneling microscopy (STM) images taken at real time during PH 3 exposure indicate that a surface phosphorus atom readily and randomly dis places one Si atom from the substrate. The ejected Si diffuses, nucleates, and incorporates itself into islands or step edges, leading to similar grow th behavior as that found in Si chemical vapor deposition. Line defects bot h perpendicular and parallel to the dimer rows are observed on the nearly P -saturated surface. Perpendicular line defects act as a strain relief mecha nism. Parallel line defects result from growth kinetics. STM images also in dicate that incorporating a small amount of phosphorus eliminates the line defects in the Si(100)-2 x n surface.