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In-situ nanoindentation electron microscopy of the nanostructured semiconducting zincite thin-films

ZnO is a semiconductor having large exciton binding energy, high electron mobility [1] and recently ability to prepare and describe its films in low-dimensional configurations. Desirable 1D configuration greatly facilitate boosting some of the materials physical properties such as efficiency of the charge transfer. For synthesis purpose, physical deposition techniques are proven to be successful but many of them require demanding conditions. On the contrary, chemical processing such as chemical bath route enables the large-scale fabrication of wellaligned ZnO nanorods at mild temperatures [2]. For characterization purpose, conventional methods fail to provide a full understanding of the investigated material, thereof it was elucidated that more detailed insight in mechanical characteristics (hardness and elastic modulus) is highly desirable, particularly in the nanoscale regime, where nanoindentation method was shown to be a flexible and useful tool [3]. Here we prepared 1D nanostructured zincite thin- films and combine investigation of their hardness and elastic modulus as well as fracture toughness with advanced imaging techniques. For characterization we focus on the in-situ micromechanical experiments with advanced nanoindentation techniques (at elevated temperatures) in the scanning and transmission electron microscopy (SEM/TEM). The course of characterization was assisted by focused ion beam (FIB) based material structuring and digital image correlation techniques to observe, describe and understand occurrence of local deformations and generally microstructural evolution. We were able to conduct a miniaturized fracture testing within the SEM and TEM apparatus. Results were utilized to qualify and quantify the materials resistance to mechanical failure such as undesirable cracking events. The mitigation of such events should enable major development role of the nanoscale optoelectronic devices. [1] A. Janotti, C. G. Van De Walle, Reports Prog. Phys. 72 (2009) 126501. [2] L. Schmidt-Mende, J. L. MacManus-Driscoll, Materials today 10 (2007) 40. [3] X.Y. Tao, X.D. Li, Nano Lett. 8 (2008) 505.

ZnO thin films, FIB, in situ, mechanical testing

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