Kukushkin Sergey A, Osipov Andrey V
Institute for Problems in Mechanical Engineering of the Russian Academy of Sciences, 199178 Saint-Petersburg, Russia.
Materials (Basel). 2021 Sep 26;14(19):5579. doi: 10.3390/ma14195579.
In the present work, a new method for obtaining silicon carbide of the cubic polytype 3C-SiC with silicon vacancies in a stable state is proposed theoretically and implemented experimentally. The idea of the method is that the silicon vacancies are first created by high-temperature annealing in a silicon substrate Si(111) doped with boron B, and only then is this silicon converted into 3C-SiC(111), due to a chemical reaction with carbon monoxide CO. A part of the silicon vacancies that have bypassed "chemical selection" during this transformation get into the SiC. As the process of SiC synthesis proceeds at temperatures of ~1350 °C, thermal fluctuations in the SiC force the carbon atom C adjacent to the vacancy to jump to its place. In this case, an almost flat cluster of four C atoms and an additional void right under it are formed. This stable state of the vacancy, by analogy with NV centers in diamond, is designated as a CV center. The CV centers in the grown 3C-SiC were detected experimentally by Raman spectroscopy and spectroscopic ellipsometry. Calculations performed by methods of density-functional theory have revealed that the CV centers have a magnetic moment equal to the Bohr magneton μB and lead to spin polarization in the SiC if the concentration of CV centers is sufficiently high.
在本工作中，从理论上提出并通过实验实现了一种获得具有稳定态硅空位的立方多型3C-SiC的新方法。该方法的思路是，首先在掺杂硼B的硅衬底Si(111)中通过高温退火产生硅空位，然后由于与一氧化碳CO发生化学反应，才将该硅转化为3C-SiC(111)。在这种转变过程中绕过“化学筛选”的一部分硅空位进入SiC。随着SiC合成过程在约1350℃的温度下进行，SiC中的热涨落迫使与空位相邻的碳原子C跳到其位置。在这种情况下，形成了一个由四个C原子组成的几乎扁平的团簇以及其下方的一个额外空位。类似于金刚石中的NV中心，这种空位的稳定态被称为CV中心。通过拉曼光谱和光谱椭偏测量对生长的3C-SiC中的CV中心进行了实验检测。用密度泛函理论方法进行的计算表明，如果CV中心的浓度足够高，CV中心具有等于玻尔磁子μB的磁矩，并导致SiC中的自旋极化。
