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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 33, Number 3
BKCSDE 33(3)
March 20, 2012 

Adsorption Mechanisms of NH3 on Chlorinated Si(100)-2 × 1 Surface
Hee Soon Lee, Cheol Ho Choi*
SIMOMM, Mechanism, Ammonia, Silicon surface, Ab initio
The potential energy surfaces of ammonia molecule adsorptions on the symmetrically chlorinated Si(100)- 2 × 1 surface were explored with SIMOMM:MP2/6-31G(d). It was found that the initial nucleophilic attack by ammonia nitrogen to the surface Si forms a SN2 type transition state, which eventually leads to an HCl molecular desorption. The second ammonia molecule adsorption requires much less reaction barrier, which can be rationalized by the surface cooperative effect. In general, it was shown that the surface Si-Cl bonds can be easily subjected to the substitution reactions by ammonia molecules yielding symmetric surface Si-NH2 bonds, which can be a good initial template for subsequent surface chemical modifications. The ammonia adsorptions are in general more facile than the corresponding water adsorption, since ammonia is better nucleophile.
775 - 778
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