Controlling Defect Formation of Nanoscale AlN: Toward Efficient Current Conduction of Ultrawide‐Bandgap Semiconductors
Controlling Defect Formation of Nanoscale AlN: Toward Efficient Current Conduction of Ultrawide‐Bandgap Semiconductors
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控制纳米级 AlN 缺陷的形成：实现超宽带隙半导体的高效电流传导
DOI：
10.1002/aelm.202000337
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发表时间：
2020
影响因子：
6.2
通讯作者：
Ahmadi, Elaheh
中科院分区：
文献类型：
--
作者：
Wu, Yuanpeng;Laleyan, David A.;Deng, Zihao;Ahn, Chihyo;Aiello, Anthony F.;Pandey, Ayush;Liu, Xianhe;Wang, Ping;Sun, Kai;Ahmadi, Elaheh
AlN、BN和金刚石等超宽带隙半导体在高效率深紫外光电子学和高功率/高频电子学方面有着巨大的应用前景，但其实际应用一直受到电流导电性差的限制。通过理论和实验相结合的研究表明，利用富N外延可以解决AlN纳米结构的关键挑战。在富N条件下，p型Al置换镁掺杂的形成能显著降低2 eV，而N空位相关的补偿缺陷的形成能增加≈3 eV，这两者都是实现高空穴浓度的必要条件。对AlN p-i-n二极管的电流−电压特性的详细分析表明，室温下的电流传导主要是空穴-载流子隧穿，而空穴-载流子隧穿直接与镁掺杂的激活能有关。在较高的镁浓度下，镁受主能级的弥散导致部分镁掺杂的激活能急剧降低，表现为67 meV的小隧道能，这解释了纳米氮化铝二极管的有效电流传导和很小的开启电压(≈5)。这项工作表明，纳米结构可以克服超宽带隙半导体的掺杂性挑战，显著提高器件的效率。
Ultrawide‐bandgap semiconductors such as AlN, BN, and diamond hold tremendous promise for high‐efficiency deep‐ultraviolet optoelectronics and high‐power/frequency electronics, but their practical application has been limited by poor current conduction. Through a combined theoretical and experimental study, it is shown that a critical challenge can be addressed for AlN nanostructures by using N‐rich epitaxy. Under N‐rich conditions, the p‐type Al‐substitutional Mg‐dopant formation energy is significantly reduced by 2 eV, whereas the formation energy for N‐vacancy related compensating defects is increased by ≈3 eV, both of which are essential to achieve high hole concentrations of AlN. Detailed analysis of the current−voltage characteristics of AlN p‐i‐n diodes suggests that current conduction is dominated by hole‐carrier tunneling at room temperature, which is directly related to the activation energy of Mg dopants. At high Mg concentrations, the dispersion of Mg acceptor energy levels leads to drastically reduced activation energy for a portion of Mg dopants, evidenced by the small tunneling energy of 67 meV, which explains the efficient current conduction and the very small turn‐on voltage (≈5 V) for the diodes made of nanoscale AlN. This work shows that nanostructures can overcome the dopability challenges of ultrawide‐bandgap semiconductors and significantly increase the efficiency of devices.
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影响因子：
10.8
作者：
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