Carrier Trapping by Vacancy-Type Defects in Mg-Implanted GaN Studied Using Monoenergetic Positron Beams
Carrier Trapping by Vacancy-Type Defects in Mg-Implanted GaN Studied Using Monoenergetic Positron Beams
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DOI：
10.1002/pssb.201700521
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发表时间：
2018-04-01
影响因子：
1.6
通讯作者：
Ishibashi, Shoji
中科院分区：
文献类型：
--
作者：
Uedono, Akira;Takashima, Shinya;Ishibashi, Shoji
利用单能正电子束对镁注入GaN中的空位型缺陷进行了探测。在室温下，Mg+离子注入形成500 nm深的盒形轮廓，其Mg浓度为1x10(17)-1x10(19)cm（-3）。在注入样品中，主要缺陷种是Ga空位（V-Ga）和氮空位（V-N）的复合物。在1000℃以上退火后，由于空位聚集，主要缺陷种变为空位团簇。随着[Mg]的减小，团聚开始温度降低。对于[Mg]1 × 10(18)cm（-3）的样品，在1100-1200℃以上退火后，空位型缺陷的正电子捕获率下降，这是由于费米能级向下移动导致缺陷电荷态从中性变为正电荷。揭示了空位型缺陷的载流子捕获/去捕获特性及其时间依赖性。
Vacancy-type defects in Mg-implanted GaN are probed using monoenergetic positron beams. Mg+ ions are implanted to provide a 500-nm-deep box profile with Mg concentrations, [Mg], of 1x10(17)-1x10(19)cm(-3) at room temperature. In the as-implanted samples, the major defect species is a complex of a Ga vacancy (V-Ga) and a nitrogen vacancy (V-N). After annealing above 1000 degrees C, the major defect species is changed to vacancy clusters due to vacancy agglomeration. This agglomeration is suppressed, and the agglomeration onset temperature is decreased with a decreasing [Mg]. For samples with [Mg]1x10(18)cm(-3), the trapping rate of positrons by vacancy-type defects decrease after annealing above 1100-1200 degrees C. This decreases is attributed to the change in the defect charge states from neutral to positive due to a downward shift of the Fermi level. The carrier trapping/detrapping properties of the vacancy-type defects and their time dependences are also revealed.