Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5424861 | Surface Science | 2007 | 7 Pages |
PH3 adsorption on Si(1Â 1Â 1)-7Â ÃÂ 7 was studied after various exposures between 0.3 and 60Â L at room temperature by means of scanning tunneling microscopy (STM). PH3-, PH2-, H-reacted, and unreacted adatoms can be identified by analyzing empty-state STM images at different sample biases. PHx-reacted rest-atoms can be observed in empty-state STM images if neighboring adatoms are hydrogen terminated. Most of the PH3 adsorbs dissociatively on the surface, generating H- and PH2-adsorbed rest-atom and adatom sites. Dangling-bonds at rest-atom sites are more reactive than adatom sites and the faulted half of the 7Â ÃÂ 7 unit cell is more reactive than the unfaulted half. Center adatoms are overwhelmingly preferred over corner adatoms for PH2 adsorption. The saturation P coverage is â¼0.18Â ML. Annealing of PH3-reacted 7Â ÃÂ 7 surfaces at 900Â K generates disordered, partially P-covered surfaces, but dosing PH3 at 900Â K forms P/Si(1Â 1Â 1)-63 surfaces. Si deposition at 510Â K leaves disordered clusters on the surface, which cannot be reordered by annealing up to 800Â K. However, annealing above 900Â K recreates P/Si(1Â 1Â 1)-63 surfaces. Surface morphologies formed by sequential rapid thermal annealing are also presented.