Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (08): 1535-1544.doi: 10.3866/PKU.WHXB20090742

• ARTICLE • Previous Articles     Next Articles

Geometries and Electronic Structures for the Adsorption of Li on Si(001) Surface with Different Coverages

NI Bi-Lian, CAI Ya-Ping, LI Yi, DING Kai-Ning, ZHANG Yong-Fan   

  1. Department of Fundamental Chemistry, College of Pharmacy, Fujian Medical University, Fuzhou 350108, P. R. China|College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, P. R. China
  • Received:2009-02-10 Revised:2009-04-16 Published:2009-07-16
  • Contact: ZHANG Yong-Fan E-mail:zhangyf@fzu.edu.cn

Abstract:

Using density functional theory, based on the pseudo-potential plane wave basis set, the geometries and  electronic structures of Li/Si(001) systems with different Li atom coverages were investigated systematically. The effect of Li adsorption on surface properties was also investigated. Our results indicated that Li atoms preferred to adsorb on high symmetry sites between adjacent Si-Si dimers and that the smallest average adsorption energy was predicted for the 0.75 monolayer (ML) coverage. By analyzing the band structures, the Si(001) surface varied from semiconductor to conductor, then to semiconductor again with increasing Li coverage. The bandgap of the Si(001) surface increased obviously at 1.00 ML coverage because of the significant destruction of surface Si-Si dimers after Li adsorption. Since electrons obviously transferred from the Li atom to the substrate, the work function of the surface decreased and oscillated with an increase in coverage. Furthermore, according to the calculated surface formation energy, the phase corresponding to 0.75 ML coverage should be difficult to observe.

Key words: Density functional theory, Alkali metal, Surface adsorption, Band structure, Si(001) surface

MSC2000: 

  • O641