Kinetics of Guided Growth of Horizontal GaN Nanowires on Flat and Faceted Sapphire Surfaces

Abstract

The bottom-up assembly of nanowires facilitates the control of their dimensions, structure, orientation and physical properties. Surface-guided growth of planar nanowires has been shown to enable their assembly and alignment on substrates during growth, thus eliminating the need for additional post-growth processes. However, accurate control and understanding of the growth of the planar nanowires were achieved only recently, and only for ZnSe and ZnS nanowires. Here, we study the growth kinetics of surface-guided planar GaN nanowires on flat and faceted sapphire surfaces, based on the previous growth model. The data are fully consistent with the same model, presenting two limiting regimes—either the Gibbs–Thomson effect controlling the growth of the thinner nanowires or surface diffusion controlling the growth of thicker ones. The results are qualitatively compared with other semiconductors surface-guided planar nanowires materials, demonstrating the generality of the growth mechanism. The rational approach enabled by this general model provides better control of the nanowire (NW) dimensions and expands the range of materials systems and possible application of NW-based devices in nanotechnology.

Nucleation of InP on Si under micro-crucibles at ultra-high vacuum using a two-step VLS process

“…Other than many applications that arise from quantum-confinement effects, such a high-aspect ratio has also been utilized as a strain relief mechanism to integrate dissimilar semiconductors [3], especially III-V on Si for light emitters [4,5]. For large-scale integration, lateral nanowires have also been developed via surface guided VLS epitaxy by pre-patterning the substrate [6,7]. This lateral geometry has simplified the integration of VLS-grown nanowires as it does not require any post-processing [8,9] to the as-grown nanowires.…”

Real-Time Study of Surface-Guided Nanowire Growth by In Situ Scanning Electron Microscopy

“…31,32 The kinetics and mechanism of surface-guided NW growth were studied comprehensively only recently and revealed the effect of dimensionality on the diffusion transport of the semiconductor materials into the catalyst droplet. 33,34 These studies present a highly predictive theoretical model of the planar growth kinetics that considers different pathways of material transport into the surface-guided NWs and shows that two main effects control the in-plane growth: the Gibbs− Thomson (GT) effect for thinner NWs and surface diffusion for thicker ones. These two opposed effects lead to a maximum NW growth rate at an optimal catalyst nanoparticle size and NW diameter.…”