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How Graphene Islands Are Unidirectionally Aligned on the Ge(110) Surface
journal contribution
posted on 2016-04-21, 00:00 authored by Jiayun Dai, Danxia Wang, Miao Zhang, Tianchao Niu, Ang Li, Mao Ye, Shan Qiao, Guqiao Ding, Xiaoming Xie, Yongqiang Wang, Paul
K. Chu, Qinghong Yuan, Zengfeng Di, Xi Wang, Feng Ding, Boris I. YakobsonThe
unidirectional alignment of graphene islands is essential to the synthesis
of wafer-scale single-crystal graphene on Ge(110) surface, but the
underlying mechanism is not well-understood. Here we report that the
necessary coalignment of the nucleating graphene islands on Ge(110)
surface is caused by the presence of step-pattern; we show that on
the preannealed Ge(110) textureless surface the graphene islands appear
nonpreferentially orientated, while on the Ge(110) surfaces with natural
step pattern, all graphene islands emerge coaligned. First-principles
calculations and theoretical analysis reveal this different alignment
behaviors originate from the strong chemical binding formed between
the graphene island edges and the atomic steps on the Ge(110) surface,
and the lattice matching at edge-step interface dictates the alignment
of graphene islands with the armchair direction of graphene along
the [−110] direction of the Ge(110) substrate.