Shiell Thomas B, Zhu Li, Cook Brenton A, Bradby Jodie E, McCulloch Dougal G, Strobel Timothy A
Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA.
Physics, School of Science, RMIT University, Melbourne, Victoria 3001 Australia.
Phys Rev Lett. 2021 May 28;126(21):215701. doi: 10.1103/PhysRevLett.126.215701.
We report the synthesis of bulk, highly oriented, crystalline 4H hexagonal silicon (4H-Si), through a metastable phase transformation upon heating the single-crystalline Si_{24} allotrope. Remarkably, the resulting 4H-Si crystallites exhibit an orientation relationship with the Si_{24} crystals, indicating a structural relationship between the two phases. Optical absorption measurements reveal that 4H-Si exhibits an indirect band gap near 1.2 eV, in agreement with first principles calculations. The metastable crystalline transition pathway provides a novel route to access bulk crystalline 4H-Si in contrast to previous transformation paths that yield only nanocrystalline-disordered materials.
我们报告了通过加热单晶硅24同素异形体时的亚稳相变来合成块状、高度取向的晶体4H六方硅（4H-Si）。值得注意的是，所得的4H-Si微晶与Si24晶体呈现出取向关系，表明这两个相之间存在结构关系。光吸收测量表明，4H-Si在1.2 eV附近表现出间接带隙，这与第一性原理计算结果一致。与之前仅产生纳米晶无序材料的转变路径相比，这种亚稳晶体转变途径为获得块状晶体4H-Si提供了一条新途径。
