Ab initio study of adsorption and decomposition of NH3 on Si(100)-(2x1)

被引:116
作者
Widjaja, Y [1 ]
Mysinger, MM [1 ]
Musgrave, CB [1 ]
机构
[1] Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA
来源
JOURNAL OF PHYSICAL CHEMISTRY B | 2000年 / 104卷 / 11期
关键词
D O I
10.1021/jp9936998
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We investigate the mechanism of NH3 adsorption and initial decomposition on the (2 x 1) reconstructed Si(100) surface using B3LYP density functional theory. The Si(100)-(2 x 1) surface is described using cluster approximation. Ammonia is found to adsorb on the "down" atom of the buckled silicon dimer with no activation barrier. We also find that only half of the surface silicon atoms are active sites for ammonia adsorption. Ammonia adsorption on the Si(100)-(2 x 1) is exothermic with an adsorption energy of 29 kcal/mol. Dissociation of the adsorbed ammonia to form NH2(a) and H(a) proceeds with a low activation energy of 5 kcal/mol below the NH3(g) and bare Si(100)-(2 x 1) energy. Our calculated recombination desorption energy of 51 kcal/mol is found to be in good agreement with the temperature-programmed desorption experimental result of 47 kcal/mol. Additionally, our calculated vibrational spectra of NH2(a) and H(a) agree within 2% of the experimental high-resolution electron energy loss spectra.
引用
收藏
页码:2527 / 2533
页数:7
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