Na 吸附在 Ir 超晶格上诱导石墨烯狄拉克锥之间的大带隙打开。

Large band gap opening between graphene Dirac cones induced by Na adsorption onto an Ir superlattice.

机构信息

Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste, Italy.

出版信息

ACS Nano. 2012 Jan 24;6(1):199-204. doi: 10.1021/nn203841q. Epub 2011 Dec 8.

DOI:10.1021/nn203841q

Abstract

We investigate the effects of Na adsorption on the electronic structure of bare and Ir cluster superlattice-covered epitaxial graphene on Ir(111) using angle-resolved photoemission spectroscopy and scanning tunneling microscopy. At Na saturation coverage, a massive charge migration from sodium atoms to graphene raises the graphene Fermi level by ~1.4 eV relative to its neutrality point. We find that Na is adsorbed on top of the graphene layer, and when coadsorbed onto an Ir cluster superlattice, it results in the opening of a large band gap of Δ(Na/Ir/G) = 740 meV, comparable to the one of Ge and with preserved high group velocity of the charge carriers.

摘要

我们使用角分辨光电子能谱和扫描隧道显微镜研究了 Na 吸附对 Ir(111)上裸露和 Ir 团簇超晶格覆盖外延石墨烯的电子结构的影响。在 Na 饱和覆盖度下，来自钠原子的大量电荷迁移将石墨烯的费米能级相对于其中性点提高了约 1.4 eV。我们发现，Na 吸附在石墨烯层的顶部，当共吸附到 Ir 团簇超晶格上时，会导致一个大的能带隙 Δ(Na/Ir/G) = 740 meV 的打开，这与 Ge 的能带隙相当，并且载流子的群速度保持很高。