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首页> 外文期刊>Physical review >Chemical trend of the formation energies of the group-Ⅲ and group-Ⅴ dopants in Si quantum dots
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Chemical trend of the formation energies of the group-Ⅲ and group-Ⅴ dopants in Si quantum dots

机译：Si量子点中Ⅲ族和Ⅴ族掺杂剂形成能的化学趋势

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Doping behavior in quantum dots (QDs) differs from that in the bulk. Despite many efforts, the doping properties are still not fully understood. Using first-principles methods, we have calculated the formation energies of various group-Ⅲ acceptors and group-Ⅴ donors doping at all nonequivalent sites in a Si QD (Si_(147)H_(100))- To analyze the trend of the formation energy, we decompose it into two terms: the unrelaxed formation energy (chemical energy) and the relaxation energy. We find that the unrelaxed formation energy generally increases as the dopant moves from the center of the QD to the surface. The variation of the unrelaxed formation energy in the surface region is explained by the variation of the local potential of the QD and the size effect. The relaxation energy gain increases as the size mismatch between the dopant and Si atom increases. Generally, the relaxation effect becomes more significant as the dopant moves toward the surface of the QD. The trend of the formation energy is determined by the two terms discussed above. If the size mismatch between the dopant and the Si atom is small, the trend of the formation energy generally follows that of the unrelaxed formation energy, increasing as the dopant moves from the center to the surface; thus, these dopants have a better chance of staying in the core region. On the other hand, if the size mismatch is large, the relaxation effect dominates and the formation energy decreases, which indicates these dopants cannot enter the core region under equilibrium growth conditions.
机译：量子点（QD）中的掺杂行为与体中的不同。尽管进行了许多努力，但是仍未完全了解掺杂性质。使用第一性原理方法，我们计算了在Si QD（Si_（147）H_（100））中所有非等价位处掺杂的Ⅲ族受体和Ⅴ族供体的形成能-分析形成趋势能量，我们将其分解为两个术语：非松弛地层能量（化学能）和松弛能。我们发现，随着掺杂剂从量子点的中心向表面移动，未松弛的形成能通常会增加。通过QD的局部电势的变化和尺寸效应来解释表面区域中的非松弛形成能的变化。随着掺杂剂和Si原子之间尺寸失配的增加，弛豫能量增益增加。通常，当掺杂剂移向QD表面时，弛豫效果会变得更加明显。地层能量的趋势由上面讨论的两个术语确定。如果掺杂剂和Si原子之间的尺寸失配较小，则形成能的趋势通常遵循未松弛形成能的趋势，并且随着掺杂剂从中心向表面移动而增加。因此，这些掺杂剂更有可能停留在核心区域。另一方面，如果尺寸不匹配大，则弛豫效应占优势，并且形成能降低，这表明这些掺杂剂在​​平衡生长条件下不能进入核心区域。

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