Molecular beam epitaxy of single crystalline GaN nanowires on a flexible Ti foil
Figure 1. (a) Photograph of the Ti foil after nanowire growth demonstrating a high degree of flexibility. [(b) and (c)] Scanning electron micrographs of the GaN nanowire ensemble grown on the Ti foil taken in bird’s eye view with (b) low and (c) high magnification. The red square in (a) is not to scale.
Figure 2. (a) Low temperature (9 K) photoluminescence spectrum of the GaN nanowire ensemble grown on the Ti foil. The corresponding spectrum of a GaN nanowire ensemble prepared on Si(111) is included for comparison. The collected spectra, normalized and shifted vertically for clarity, indicate that nanowires grown on Ti foils exhibit a similar crystalline perfection, a lower degree of coalescence, a higher concentration of stacking faults, and a reduced density of inversion domain boundaries than those prepared on Si substrates. (b) Room-temperature photoluminescence spectra of the GaN nanowire ensemble grown on the Ti foil for an infinite and a convex curvature of the substrate with a 4mm radius. The collected spectra indicate that as–grown nanowires are well anchored to the Ti foil and do not degrade upon substrate bending. The inset shows a photograph of the bent Ti foil taken during the acquisition of the experimental data.
In this work, we demonstrate the self–assembled growth of an ensemble of single crystalline, uncoalesced, and vertically aligned GaN nanowires on a flexible Ti foil using plasma–assisted molecular beam epitaxy. The structural and optical properties of the sample, investigated by transmission electron microscopy and photoluminescence spectroscopy, are compared with those of standard GaN nanowire ensembles prepared on Si(111) substrates. We find that both the structural perfection and the low temperature photoluminescence spectra of the nanowire ensembles prepared on Ti foils and Si substrates are fairly comparable. Furthermore, we do not observe any degradation of the luminescence upon bending the nanowire ensemble prepared on the foil down to a small curvature radius of 4mm. Therefore, a GaN nanowire ensemble on a Ti foil is indeed a highly flexible system suitable for the realization of bendable GaN-based devices. The present results pave the way for the realization of flexible GaN nanowire-based electronic and optoelectronic devices on metal foils.
| 1 | Author | G. Calabrese , P. Corfdir , G. Gao , C. Pfüller , A. Trampert , O. Brandt , L. Geelhaar , S. Fernández-Garrido |
| Title |
Molecular beam epitaxy of single crystalline GaN nanowires on a flexible Ti foil |
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| Source | Appl. Phys. Lett. , 108 , 202101 ( 2016 ) | |
| DOI : 10.1063/1.4950707 | Download: PDF | Cite : Bibtex RIS | ||
Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin e.V.
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