Evidence of Two-Dimensional Hole Gas in p-Type AlGaN/AlN/GaN Heterostructures
Evidence of Two-Dimensional Hole Gas in p-Type AlGaN/AlN/GaN Heterostructures
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DOI：
10.1143/apex.2.121001
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发表时间：
2009-11
影响因子：
2.3
通讯作者：
Qiyuan Wei;Zhihao Wu;K. Sun;F. Ponce;J. Hertkorn;F. Scholz
中科院分区：
文献类型：
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作者：
Qiyuan Wei;Zhihao Wu;K. Sun;F. Ponce;J. Hertkorn;F. Scholz
用电子全息术研究了调制掺杂p型AlGaN/AlN/GaN异质结的电子能带结构，其中AlGaN层是组分渐变的。静电势能分布和二维空穴气（2DHG）的分布已被测量与高空间分辨率的异质结构。已观察到的电位分布的正曲率，它被认为是在AlN/GaN界面处的2DHG中的空穴积累的证据。还观察到2DHG的势垒受到p-AlGaN层中的受主电离的极大影响。对于相邻沟道之间的空穴传输的能量势垒的性质的这种知识在p型AlGaN/GaN异质结构的垂直导电性的优化中是重要的，p型AlGaN/GaN异质结构可以用作GaN基发光二极管或激光二极管中的电流扩展层。
The electronic band structure of a modulation-doped p-type AlGaN/AlN/GaN heterostructure, where the AlGaN layer is compositionally graded, has been studied by electron holography. The electrostatic potential energy profile and the two-dimensional hole gas (2DHG) distribution have been measured with high spatial resolution across the heterostructure. A positive curvature in the potential profile has been observed, and it is considered as evidence for the accumulation of holes in a 2DHG at the AlN/GaN interface. It is also observed that the potential barrier for the 2DHG is greatly affected by acceptor ionization in the p-AlGaN layer. This knowledge of nature of the energy barriers for hole transfer between adjacent channels is important in the optimization of vertical conductivity of p-type AlGaN/GaN heterostructures, which can be used as current spreading layers in GaN-based light emitting diodes or laser diodes.