Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides.
Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides.
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DOI：
10.1038/srep19537
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发表时间：
2016-01-18
影响因子：
4.6
通讯作者：
Zhang Y
中科院分区：
文献类型：
--
作者：
Liu Z;Yi X;Yu Z;Yuan G;Liu Y;Wang J;Li J;Lu N;Ferguson I;Zhang Y
在这项工作中，提出了一种在高禁带隙氮化物半导体中实现高效p型掺杂的新策略，以克服高激活能这一根本问题，并从理论上进行了研究，并进行了实验验证。具体地说，在AlxGa1−xN/GaN超晶格结构中，通过在AlxGa1−xN势垒中调制掺杂镁，在整个材料中产生了高密度的空穴。获得了高达1.1 × 1018 cm−3的空穴浓度，比通常直接掺杂GaN的空穴浓度高出一个数量级。第一性原理计算结果表明，Mg2p杂质与宿主N2p轨道之间的耦合和杂化是GaN势垒中产生共振态的主要原因，进而导致高的空穴浓度。我们希望这种方法同样适用于其他高带隙材料，在那里高效的p型制作是困难的。此外，还提出了一个双载流子霍尔效应模型来描述和区分超晶格掺杂系统中通常共存的体空穴和二维空穴的特性。本文所报道的模型也可以用来解释以前许多报告中观察到的异常冻结效应。
In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa1−xN/GaN superlattice structure, by modulation doping of Mg in the AlxGa1−xN barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 1018 cm−3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports.