Defect characterization and analysis of III‐V nanowires grown by Ni‐promoted MBE
Defect characterization and analysis of III‐V nanowires grown by Ni‐promoted MBE
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Ni促进MBE生长的III-V纳米线的缺陷表征和分析
DOI：
10.1002/pssa.200780132
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
H. Riechert
中科院分区：
文献类型：
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作者：
L. Lari;R. Murray;M. Gass;T. Bullough;P. Chalker;J. Kioseoglou;G. Dimitrakopulos;T. Kehagias;P. Komninou;T. Karakostas;C. Chèze;L. Geelhaar;H. Riechert
我们报告了通过射频等离子体辅助分子束外延（PAMBE）在c-蓝宝石衬底上生长的GaN和Al0.2Ga0.8N纳米线（NW）的透射电子显微镜（TEM）和扫描透射电子显微镜（STEM）分析。传统的TEM图像从衬底上去除的单纳米线表现出高密度的基底堆垛层错。使用畸变校正SuperSTEM设施进行进一步分析。几何相位分析（GPA）应用于此数据揭示了固有的基底层错引入的特征晶格位移。发现用于促进NW型生长的镍基“种子”位于每个纳米线的尖端。对这些种子的点阵图像进行了不同类型的分析，包括GPA、投影法分析和HREM图像的快速傅立叶变换。所有这三种方法得到的晶格常数和位移具有良好的一致性。在GaN纳米线体中测得的晶格值与弛豫体GaN的晶格常数很好地一致。对于晶种颗粒，在实验误差范围内，所得晶格间距可归因于氧化镍、Ni 3Ga或中间合金相。在AlGaN纳米线中测量缺陷密度，发现其为106 cm-1的量级。的结果进行了严格的讨论有关的可能的生长机制的纳米线。（© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA，魏因海姆）
We report on transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) analysis of GaN and Al0.2Ga0.8N nanowires (NWs) grown by radio frequency plasma assisted Molecular Beam Epitaxy (PAMBE) on c‐sapphire substrates. Conventional TEM images of single nanowires removed from the substrate exhibit a high density of basal stacking faults. Further analyses were performed using the aberration‐corrected SuperSTEM facility. Geometric phase analysis (GPA) was applied to this data revealing the characteristic lattice displacement introduced by intrinsic basal stacking faults. The nickel‐based “seeds”, which were employed to promote the NW‐type growth, are found to be situated at the tip of each nanowire. Different types of analyses were applied to lattice images of these seeds including GPA, projection method analysis and Fast Fourier transform of the HREM images. All three approaches yielded lattice constants and displacements with good agreement. The measured lattice values in the GaN nanowire body were in good agreement with the lattice constants of relaxed bulk GaN. For the seed particles the resulting lattice spacing was attributable, within the experimental error, to either nickel oxide, Ni3Ga, or an intermediate alloy phase. The defect density was measured in the AlGaN nanowires and was found to be in the order of 106 cm–1. The results are critically discussed in relation to the possible growth mechanisms of the NWs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)