Abstract Honeycomb-chain-channel (HCC) and π-bond Seiwatz chain (SC) are the well-known reconstructions induced by alkaline earth metal on Si(111) surface. Here we identify by ab initio calculations a stable intermediate phase of Sr/Si(111)-(5×4) HCC+SC. This new reconstruction satisfies the electron counting rule with the Sr coverage of 3/10 monolayer. In each (5×4) surface unit cell, six Sr atoms are distributed as evenly as possible in the two channels. One of the channels contains two Sr atoms on the top site T4 and one Sr atom on the hollow site H3, while another channel contains two Sr atoms on site H3 and one on site T4. Electronic band structures and band-decomposed charge density distributions show that there are seven occupied surface states ( S 1 – S 5 , Σ 1 and Σ 2 ) and two unoccupied surface states ( S 6 and S 7 ) near the Fermi level. Moreover, we find that this new (5×4) surface structure is a semiconductor with a surface band gap of 0.62 eV, determined by the S 2 and S 6 surface states in honeycomb Si chains.

中文翻译：

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Si(111)表面Sr诱导(5×4)重构的结构稳定性和电子特性

摘要 蜂窝链通道 (HCC) 和 π 键 Seiwatz 链 (SC) 是众所周知的由碱土金属在 Si(111) 表面诱导的重构。在这里，我们通过从头算计算确定了 Sr/Si(111)-(5×4) HCC+SC 的稳定中间相。这种新的重建满足电子计数规则，Sr 覆盖率为 3/10 单层。在每个 (5×4) 表面晶胞中，六个 Sr 原子尽可能均匀地分布在两个通道中。其中一个通道在顶部 T4 位点包含两个 Sr 原子，在中空位点 H3 包含一个 Sr 原子，而另一个通道在 H3 位点包含两个 Sr 原子，在 T4 位点包含一个 Sr 原子。电子能带结构和能带分解电荷密度分布表明，有七种占据的表面态（S 1 – S 5 ，Σ 1 和 Σ 2 ）和费米能级附近的两个未占据表面态（S 6 和 S 7 ）。此外，我们发现这种新的 (5×4) 表面结构是一种表面带隙为 0.62 eV 的半导体，由蜂窝状硅链中的 S 2 和 S 6 表面态决定。