On compensation in Si-doped AlN
On compensation in Si-doped AlN
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DOI：
10.1063/1.5022794
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发表时间：
2018-04
影响因子：
4
通讯作者：
J. S. Harris;J. Baker;Benjamin E. Gaddy;I. Bryan;Z. Bryan;Kelsey J. Mirrielees;P. Reddy;R. Collazo;Z. Sitar;D. Irving
中科院分区：
文献类型：
--
作者：
J. S. Harris;J. Baker;Benjamin E. Gaddy;I. Bryan;Z. Bryan;Kelsey J. Mirrielees;P. Reddy;R. Collazo;Z. Sitar;D. Irving
在AlN或富Al的AlGaN中，在较宽的载流子浓度范围内实现可控的n型掺杂对于实现高功率电子器件和深紫外光源的下一代应用至关重要。硅在AlN中不像在GaN中那样是类氢施主；尽管如此，通过在生长过程中增加施主浓度，载流子浓度应该是可控的，尽管效率较低。在低掺杂水平下，硅含量的增加会导致自由电子相应增加。但问题是，这种趋势在较高掺杂水平下无法持续。实际上，硅浓度的进一步增加会导致自由电子浓度降低；这通常被称为补偿拐点。虽然这种降低的性质已归因于多种补偿缺陷，但与拐点相关的主要缺陷的机制和特性尚未最终确定。使用杂化交换 - 关联泛函的密度泛函理论计算已确定VAl + nSiAl复合物对于从机制上理解AlN中高硅极限的补偿至关重要，而次要杂质和空位往往在低硅极限的补偿中占主导地位。计算了这些缺陷在AlN中的形成能和光学特征，并在巨正则电荷平衡求解器中用于确定载流子浓度随硅含量的变化。结果在定性上重现了实验观察到的补偿拐点。此外，这些计算预测了高掺杂和低掺杂极限下存在的光发射的变化，这通过详细的光致发光测量得到了证实。在AlN或富Al的AlGaN中，在较宽的载流子浓度范围内实现可控的n型掺杂对于实现高功率电子器件和深紫外光源的下一代应用至关重要。硅在AlN中不像在GaN中那样是类氢施主；尽管如此，通过在生长过程中增加施主浓度，载流子浓度应该是可控的，尽管效率较低。在低掺杂水平下，硅含量的增加会导致自由电子相应增加。但问题是，这种趋势在较高掺杂水平下无法持续。实际上，硅浓度的进一步增加会导致自由电子浓度降低；这通常被称为补偿拐点。虽然这种降低的性质已归因于多种补偿缺陷，但与拐点相关的主要缺陷的机制和特性尚未最终确定。密度泛函理论计算……
Controllable n-type doping over wide ranges of carrier concentrations in AlN, or Al-rich AlGaN, is critical to realizing next-generation applications in high-power electronics and deep UV light sources. Silicon is not a hydrogenic donor in AlN as it is in GaN; despite this, the carrier concentration should be controllable, albeit less efficiently, by increasing the donor concentration during growth. At low doping levels, an increase in the Si content leads to a commensurate increase in free electrons. Problematically, this trend does not persist to higher doping levels. In fact, a further increase in the Si concentration leads to a decrease in free electron concentration; this is commonly referred to as the compensation knee. While the nature of this decrease has been attributed to a variety of compensating defects, the mechanism and identity of the predominant defects associated with the knee have not been conclusively determined. Density functional theory calculations using hybrid exchange-correlation functionals have identified VAl+nSiAl complexes as central to mechanistically understanding compensation in the high Si limit in AlN, while secondary impurities and vacancies tend to dominate compensation in the low Si limit. The formation energies and optical signatures of these defects in AlN are calculated and utilized in a grand canonical charge balance solver to identify carrier concentrations as a function of Si content. The results were found to qualitatively reproduce the experimentally observed compensation knee. Furthermore, these calculations predict a shift in the optical emissions present in the high and low doping limits, which is confirmed with detailed photoluminescence measurements.Controllable n-type doping over wide ranges of carrier concentrations in AlN, or Al-rich AlGaN, is critical to realizing next-generation applications in high-power electronics and deep UV light sources. Silicon is not a hydrogenic donor in AlN as it is in GaN; despite this, the carrier concentration should be controllable, albeit less efficiently, by increasing the donor concentration during growth. At low doping levels, an increase in the Si content leads to a commensurate increase in free electrons. Problematically, this trend does not persist to higher doping levels. In fact, a further increase in the Si concentration leads to a decrease in free electron concentration; this is commonly referred to as the compensation knee. While the nature of this decrease has been attributed to a variety of compensating defects, the mechanism and identity of the predominant defects associated with the knee have not been conclusively determined. Density functional theory calculations using hybrid exchange-correlation f...