Adsorption and dissociation of disilane on Si(001) studied by STM

Decomposition ofSiH3toSiH2on Si(100)-Lim1, Tok2, Kang3 2006Phys. Rev. B

“…As suggested in the STM study by Bronikowski et al, 7 hydrogen can subsequently diffuse away, leaving silylene adsorbed in the intrarow configuration. We discuss this further in the next section.…”

“…6,7 In the sequential images of Si͑100͒-͑1 ϫ 2͒, the adsorption of the silyl group and its subsequent dissociation reaction into intrarow silylene and hydrogen have been observed. However, this is not conclusive evidence for a pathway leading directly from adsorbed silyl to the intrarow configuration as the latter can also be formed from the relaxation of the silylene group from a higher energy configuration after the decomposition process.…”

“…The bond lengths and angles denoted by a to k are given in Table I. Indeed, the on-dimer structure was ruled out by early work on the basis of the small bond angle. 7 It is interesting to note that the adsorption of an on-dimer silylene group on a dimer leaves the adjacent clean dimer slightly shortened. Table II is a summary of adsorption energetics, including results obtained in previous calculations.…”

“…Surface analysis techniques such as secondary-ionmass spectroscopy ͑SIMS͒, temperature-programmed desorption ͑TPD͒, and low-energy electron diffraction ͑LEED͒ have been used by Gates et al to study the decomposition mechanism of SiH x species on the Si͑100͒-͑1 ϫ 2͒ surface. [8][9][10][11] This work, as well as many others, 6,7,[12][13][14][15][16][17][18] shows that the silyl group produced by the decomposition of silane and disilane is metastable and has an average lifetime on the order of a few minutes at room temperature. 6 Scanning tunnel microscopy ͑STM͒ studies also show that the silylene group resulting from silyl decomposition remains stable below 470 K. 19 Silylene is therefore believed to be the predominant species occurring on Si͑100͒-͑1 ϫ 2͒ during growth by GSMBE.…”

“…The equilibrium adsorption sites of the silylene are now rather well established. [2][3][4][5][6][7] Without adsorbed hydrogen atoms in the vicinity of the silylene group, the most favorable adsorption configuration is the on-dimer structure with the silylene adsorbed onto a surface dimer leaving the surface dimer bond intact. With hydrogen atoms coadsorbed in the vicinity of the silylene, the more stable configuration is the intrarow structure with the silylene adsorbed on one side of the dimer row between two neighboring dimers.…”