Polytypism in GaAs/GaNAs core?shell nanowires
Polytypism in GaAs/GaNAs core?shell nanowires
复制标题
GaAs/GaNAs核壳纳米线的多型性
DOI：
10.1088/1361-6528/abb904
复制
发表时间：
2020
期刊：
影响因子：
3.5
通讯作者：
Ishikawa F
中科院分区：
文献类型：
--
作者：
Yukimune M;Fujiwara R;Mita T;Ishikawa F
本文报道了GaAs和GaAs/ GaAs/ GaAs核心-多壳纳米线的晶体结构。通过x射线衍射（XRD）和电子背散射衍射（EBSD）的统计分析，从统计学和微观角度分析了NWs中锌闪锌矿（ZB）和纤锌矿（WZ）的多型性。XRD分析表明，氮浓度越高，NWs中WZ片段的比例越小。随着ga壳中氮含量的增加，ZB峰位置向更高角度移动，WZ峰强度减小。EBSD测量也证实了在所有NWs中ZB和WZ多型共存。它们的多型基因沿着长度变化。在所有NWs的ZB段均观察到孪晶缺陷。独特的晶粒图和晶粒尺寸分布表明，在GaAs/ GaAs/ GaAs NW中，WZ段减少，与XRD结果一致。显微镜下观察到多型从内核侧的WZ向外壳表面的ZB切换的局部区域。总的来说，我们认为在GaAs NWs中WZ多型型的减少是由于生长具有较小晶格常数的GaAs壳所引起的应变。
We report the crystal structures of GaAs and GaAs/GaNAs/GaAs core–multishell nanowires (NWs). From statistical investigations by x-ray diffraction (XRD) and electron backscattered diffraction (EBSD) pattern analysis, we statistically and microscopically resolve the zinc-blende (ZB) and wurtzite (WZ) polytypism within the NWs. The XRD analysis shows a smaller fraction of WZ segments in the NWs with a larger concentration of nitrogen. With increasing nitrogen content in the GaNAs shell, the ZB peak position shifts toward higher angles and the WZ peak intensity decreases. The EBSD measurements also confirm the coexistence of ZB and WZ polytypes in all of the NWs. Their polytype switches along the length. Twin defects are observed in the ZB segments in all of the NWs. The unique grain map and grain size distribution show a decrease of the WZ segments in the GaAs/GaNAs/GaAs NW, in agreement with the XRD results. Microscopically, the local area where the polytype switches from WZ in the inner-core side to ZB toward the outer-shell surface is observed. Overall, we propose that the WZ polytype in the GaAs NWs decreases because of the strain induced by the growth of the GaNAs shell with a smaller lattice constant.