单空位缺陷对石墨纳米带电子结构和输运性质的影响

Study on electronic structure and transport properties of graphene nanoribbons with single vacancy defects

基于第一性原理电子结构和输运性质计算,研究了单空位缺陷对单层石墨纳米带(包括zigzag型和armchair型带)电子性质的影响.研究发现,单空位缺陷使石墨纳米带在费米面上出现一平直的缺陷态能带;单空位缺陷的引入使zigzag型半导体性的石墨纳米带变为金属性,这在能带工程中有重要的应用价值;奇数宽度的armchair型石墨纳米带表现出金属特性,有着很好的导电性能,同时,偶数宽度的armchair型石墨带虽有金属性的能带结构,但却有类似半导体的伏安特性;单空位缺陷使得奇数宽度的armchair石墨纳米带导电性能减弱,使得偶数宽度的armchair石墨纳米带导电性能明显增强.

Based on first-principles electronic structure and transport calculations,we have studied electronic structure and transport properties of graphene nanoribbons with single vacancy defects.It is shown that introduction of the single vacancy defects leads to a flat band belt at the Fermi energy level for graphene nanoribbons and the semiconductor-metal transition in zigzag semiconducting graphene nanoribbons,which is useful in the energy-band engineering.Armchair graphene nanoribbons with odd width are metallic with good electric conduction while armchair graphene nanoribbons with even width have metallic band structures with character of the group IV semiconductor.Single vacancy defects weakens the conduction of armchair graphene nanoribbons with odd width while obviously strengthens the conduction of armchair graphene nanoribbons with even width.