Lithium Intercalation Induced Decoupling of Epitaxial Graphene on SiC(0001): Electronic Property and Dynamic Process

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• 作者：Yuanchang Li ; Gang Zhou ; Jia Li ; Jian Wu ; Bing-Lin Gu ; Wenhui Duan
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 8, 2011
• 年：2011
• 卷：115
• 期：48
• 页码：23992-23997
• 全文大小：876K
• 年卷期：v.115,no.48(December 8, 2011)
• ISSN：1932-7455

文摘

This work presents first-principles investigation of the dynamic process of lithium (Li) penetration through the buffer layer on 6H-SiC(0001) surface as well as the Li-insertion-induced change of electronic structure. It is found that the penetration is kinetically forbidden for perfect buffer layer because of the size confinement of its honeycomb structure. From the analysis of rate coefficient under real experimental conditions, topological defects no smaller than 8-membered ring are predicted to be essential for Li intercalation. Along with the Li insertion, the electronic property of the buffer layer is changed from n-type doping (Li adsorption) to that of quasi-free-standing graphene (Li intercalation). It is the electron injection by Li that results in the dissociation of the Si鈥揅 bonds and the decoupling of Li-intercalated buffer layer from the substrate. Moreover, we demonstrate the influence of such topological defects on the electronic property of epitaxial graphene, which provides some useful hints for understanding the observed gap and midgap state behavior.