Exchange between deep donors in semiconductors: A quantum defect approach
Exchange between deep donors in semiconductors: A quantum defect approach
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半导体深层供体之间的交换：量子缺陷方法
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
A. Fisher
中科院分区：
文献类型：
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作者：
Wei Wu;A. Fisher
半导体中缺陷之间的交换相互作用通常在有效质量理论中使用标度类氢波函数来处理。然而，这样的波函数仅适用于浅杂质;在这里，我们提出了一个简单但强大的概括来处理深施主，其中我们使用完善的量子亏损理论来处理波函数的长程部分，并包括模型中心单元校正以将束缚态本征值固定在实验观察值。这使我们能够计算结合能对交换相互作用的影响作为供体距离的函数;这是一个重要的数量，因为最近有人提出使用深供体进行量子信息处理。正如预期的那样，交换相互作用被抑制或增加，相比类氢的情况下，通过更大的本地化或离域的波函数的深捐助者或“超浅”捐助者的结合能小于类氢值。计算结果进行了比较与一个简单的缩放海特勒-伦敦类氢交换;缩放类氢结果给出正确的数量级，但未能定量再现我们的计算。我们计算了硅中施主交换，包括施主对沿沿着100方向的谷间干扰项，并给出了施主类型对不同浓度下最近邻交换常数分布的影响。我们的方法可以用来计算任意结合能的两个施主电子之间的交换相互作用。
Exchange interactions among defects in semiconductors are commonly treated within effective-mass theory using a scaled hydrogenic wave function. However, such a wave function is only applicable to shallow impurities; here, we present a simple but robust generalization to treat deep donors, in which we treat the long-range part of the wave function using the well-established quantum defect theory, and include a model central-cell correction to fix the bound-state eigenvalue at the experimentally observed value. This allows us to compute the effect of binding energy on exchange interactions as a function of donor distance; this is a significant quantity given recent proposals to carry out quantum information processing using deep donors. As expected, exchange interactions are suppressed or increased, compared to the hydrogenic case, by the greater localization or delocalization of the wave functions of deep donors or “supershallow” donors with binding energy less than the hydrogenic value. The calculated results are compared with a simple scaling of the Heitler-London hydrogenic exchange; the scaled hydrogenic results give the correct order of magnitude but fail to reproduce quantitatively our calculations. We calculate the donor exchange in silicon including intervalley interference terms for donor pairs along the 100 direction, and also show the influence of the donor type on the distribution of nearest-neighbor exchange constants at different concentrations. Our methods can be used to compute the exchange interactions between two donor electrons with arbitrary binding energy.