A theoretical study of step edge geometry on sapphire(0001) and its effect on ZnO nucleation
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Step-edge-induced nucleation plays a key role in controlling the growth of novel nanostructures and low-dimensional materials. However, it is difficult to experimentally determine the step edge structures of complex metal oxides. In this work, we present a detailed theoretical study of the stability of stoichiometric steps on sapphire(0001). Based on first-principles calculations and excess charge computation by Finnis’ approach, a pair of non-polar step edges are determined to be the most stable. By studying the adsorption characteristics of ZnO and combining previous works, we successfully explained how growth temperature and deposition rate affect the in-plane orientation of ZnO grown on sapphire(0001). The knowledge on the step edge structures and nucleation patterns would benefit the study on step-edge-guided nanostructure growth.
Keywordsstepped sapphire surface first-principles excess charge step-edge-induced nucleation
This work was supported by the National Natural Science Foundation of China under Grant Nos. 11274179 and 11574157 and the National 973 Projects of China under Grant No. 2012CB921900.
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