Croot Alex, Othman M Zamir, Conejeros Sergio, Fox Neil A, Allan Neil L
H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
J Phys Condens Matter. 2018 Oct 24;30(42):425501. doi: 10.1088/1361-648X/aade16. Epub 2018 Aug 31.
Substitutional clusters of multiple light element dopants are a promising route to the elusive shallow donor in diamond. To understand the behaviour of co-dopants, this report presents an extensive first principles study of possible clusters of boron and nitrogen. We use periodic hybrid density functional calculations to predict the geometry, stability and electronic excitation energies of a range of clusters containing up to five N and/or B atoms. Excitation energies from hybrid calculations are compared to those from the empirical marker method, and are in good agreement. When a boron-rich or nitrogen-rich cluster consists of three to five atoms, the minority dopant element-a nitrogen or boron atom respectively-can be in either a central or peripheral position. We find B-rich clusters are most stable when N sits centrally, whereas N-rich clusters are most stable with B in a peripheral position. In the former case, excitation energies mimic those of the single boron acceptor, while the latter produce deep levels in the band-gap. Implications for probable clusters that would arise in high-pressure high-temperature co-doped diamond and their properties are discussed.
多个轻元素掺杂剂的替代团簇是实现难以捉摸的金刚石浅施主的一条有前景的途径。为了理解共掺杂剂的行为，本报告对硼和氮的可能团簇进行了广泛的第一性原理研究。我们使用周期性杂化密度泛函计算来预测一系列包含多达五个氮和/或硼原子的团簇的几何结构、稳定性和电子激发能。将杂化计算得到的激发能与经验标记法得到的激发能进行比较，两者吻合良好。当富含硼或富含氮的团簇由三到五个原子组成时，少数掺杂元素（分别为氮或硼原子）可以处于中心或外围位置。我们发现，当氮位于中心时，富含硼的团簇最稳定，而当硼处于外围位置时，富含氮的团簇最稳定。在前一种情况下，激发能类似于单硼受主的激发能，而在后一种情况下，会在带隙中产生深能级。讨论了在高温高压共掺杂金刚石中可能出现的团簇及其性质的影响。
