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Issue 21, 2017
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Surface passivation and self-regulated shell growth in selective area-grown GaN–(Al,Ga)N core–shell nanowires

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Abstract

The large surface-to-volume ratio of GaN nanowires implicates sensitivity of the optical and electrical properties of the nanowires to their surroundings. The implementation of an (Al,Ga)N shell with a larger band gap around the GaN nanowire core is a promising geometry to seal the GaN surface. We investigate the luminescence and structural properties of selective area-grown GaN–(Al,Ga)N core–shell nanowires grown on Si and diamond substrates. While the (Al,Ga)N shell allows a suppression of yellow defect luminescence from the GaN core, an overall intensity loss due to Si-related defects at the GaN/(Al,Ga)N interface has been observed in the case of Si substrates. Scanning transmission electron microscopy measurements indicate a superior crystal quality of the (Al,Ga)N shell along the nanowire side facets compared to the (Al,Ga)N cap at the top facet. A nucleation study of the (Al,Ga)N shell reveals a pronounced bowing of the nanowires along the c-direction after a short deposition time which disappears for longer growth times. This is assigned to an initially inhomogeneous shell nucleation. A detailed study of the proceeding shell growth allows the formulation of a strain-driven self-regulating (Al,Ga)N shell nucleation model.

Graphical abstract: Surface passivation and self-regulated shell growth in selective area-grown GaN–(Al,Ga)N core–shell nanowires

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Publication details

The article was received on 03 Feb 2017, accepted on 07 May 2017 and first published on 11 May 2017


Article type: Paper
DOI: 10.1039/C7NR00802C
Citation: Nanoscale, 2017,9, 7179-7188
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    Surface passivation and self-regulated shell growth in selective area-grown GaN–(Al,Ga)N core–shell nanowires

    M. Hetzl, J. Winnerl, L. Francaviglia, M. Kraut, M. Döblinger, S. Matich, A. Fontcuberta i Morral and M. Stutzmann, Nanoscale, 2017, 9, 7179
    DOI: 10.1039/C7NR00802C

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