Luna Esperanza, Grandal Javier, Gallardo Eva, Calleja José M, Sánchez-García Miguel Á, Calleja Enrique, Trampert Achim
1Paul-Drude-Institut für Festkörperelektronik,Hausvogteiplatz 5-7,D-10117 Berlin,Germany.
2Departamento de Física de Materiales,Universidad Autónoma de Madrid,E-28049 Madrid,Spain.
Microsc Microanal. 2014 Oct;20(5):1471-8. doi: 10.1017/S1431927614013038. Epub 2014 Aug 26.
We discuss observations of InN nanowires (NWs) by plan-view high-resolution transmission electron microscopy (TEM). The main difficulties arise from suitable methods available for plan-view specimen preparation. We explore different approaches and find that the best results are obtained using a refined preparation method based on the conventional procedure for plan-view TEM of thin films, specifically modified for the NW morphology. The fundamental aspects of such a preparation are the initial mechanical stabilization of the NWs and the minimization of the ion-milling process after dimpling the samples until perforation. The combined analysis by plan-view and cross-sectional TEM of the NWs allows determination of the degree of strain relaxation and reveals the formation of an unintentional shell layer (2-3-nm thick) around the InN NWs. The shell layer is composed of bcc In2O3 nanocrystals with a preferred orientation with respect to the wurtzite InN: In2O3 [111] || InN [0001] and In2O3<110>||InN<1120>.
我们讨论了通过平面视图高分辨率透射电子显微镜（TEM）对氮化铟（InN）纳米线（NWs）的观察。主要困难来自于适用于平面视图样品制备的可用方法。我们探索了不同的方法，发现基于薄膜平面视图TEM的传统程序并针对NW形态进行专门修改的精细制备方法能获得最佳结果。这种制备的基本方面是NWs的初始机械稳定以及在样品凹陷直至穿孔后使离子研磨过程最小化。通过对NWs进行平面视图和横截面TEM的联合分析，可以确定应变弛豫程度，并揭示在InN NWs周围形成了一个无意的壳层（2 - 3纳米厚）。该壳层由体心立方（bcc）In2O3纳米晶体组成，相对于纤锌矿InN具有择优取向：In2O3 [111] || InN [0001] 和In2O3<110>||InN<1120>。
