Investigation of III–V Nanowires by Plan-View Transmission Electron Microscopy: InN Case Study

Abstract 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<$$ 11\bar 20 $$>.