Why do nanowires grow with their c-axis vertically-aligned in the absence of epitaxy?

Images of uniform and upright nanowires are fascinating, but often, they are quite puzzling, when the substrate is clearly not an epitaxial template. Here, we reveal the physics underlying one such hidden growth guidance mechanism through a specific example - the case of ZnO nanowires grown on silic...

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Bibliographic Details
Published in:Scientific reports 2020-04, Vol.10 (1), p.6554-6554, Article 6554
Main Authors: Azulay, Almog R, Turkulets, Yury, Gaudio, Davide Del, Goldman, R S, Shalish, Ilan
Format: Article
Language:English
Subjects:
Electric fields
Nanotechnology
Nanowires
Polarity
Self-assembly
Semiconductors
Silicon oxide
Surface charge
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Summary:Images of uniform and upright nanowires are fascinating, but often, they are quite puzzling, when the substrate is clearly not an epitaxial template. Here, we reveal the physics underlying one such hidden growth guidance mechanism through a specific example - the case of ZnO nanowires grown on silicon oxide. We show how electric fields exerted by the insulating substrate may be manipulated through the surface charge to define the orientation and polarity of the nanowires. Surface charge is ubiquitous on the surfaces of semiconductors and insulators, and as a result, substrate electric fields need always be considered. Our results suggest a new concept, according to which the growth of wurtzite semiconductors may often be described as a process of electric-charge-induced self-assembly, wherein the internal built-in field in the polar material tends to align in parallel to an external field exerted by the substrate to minimize the interfacial energy of the system.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-020-63500-y