Structural transition at the subsurface of few-layer Bi(110) film during the growth
Structural transition at the subsurface of few-layer Bi(110) film during the growth
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DOI：
10.1103/physrevmaterials.7.033404
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发表时间：
2023-03
影响因子：
3.4
通讯作者：
T. Shirasawa;W. Voegeli;E. Arakawa;Ryota Ushioda;K. Nakatsuji;H. Hirayama
中科院分区：
文献类型：
--
作者：
T. Shirasawa;W. Voegeli;E. Arakawa;Ryota Ushioda;K. Nakatsuji;H. Hirayama
用实时X射线晶体截断棒散射测量方法研究了Si（111）衬底上Bi（110）外延薄膜的结构和生长行为。该膜生长在双层的单位高达四个原子层，并显示出准逐层生长以上的四个层，其中均匀的层高度域优先形成。结果表明，偶数层高畴完全由黑磷类双层组成，而奇数层高畴在顶层双层之下有一个额外的体Bi（110）类双层.这表明，当在偶数或奇数畴上生长额外的单层时，在表面下发生结构变化。Monte Carlo模拟表明，偶数结构的自由能比奇数结构的自由能小，导致择优形成，而在偶数/奇数畴界处的小界面能允许生长过程中的频繁跃迁。
The structure and growth behavior of Bi(110) ultrathin films on Si(111)-substrate are studied using real-time x-ray crystal truncation rod scattering measurements. The film grows in units of bilayers up to four atomic layers and shows a quasi–layer-by-layer growth above four layers in which even-layer-height domains are preferentially formed. It is revealed that the even-layer-height domains fully consist of black-phosphorus-like paired layers while the odd-layer-height domains have an additional bulk-Bi(110)-like layer beneath the top bilayer. This suggests that a structure change occurs at the subsurface when an additional single layer grows on the even or odd domains. Monte Carlo simulations indicate that a smaller free energy of the even structure than the odd structure leads to the preferential formation and that a small interface energy at the even/odd domain boundary allows the frequent transitions during the growth.