Self-Assembled formation of long, thin, and uncoalesced GaN nanowires on crystalline TiN films

Abstract

We investigate in detail the self-assembled nucleation and growth of GaN nanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate that this type of substrate allows the growth of long and thin GaN nanowires that do not suffer from coalescence, which is in contrast to the growth on Si and other substrates. Only beyond a certain nanowire length that depends on the nanowire number density and exceeds here 1.5 μm, coalescence takes place by bundling, i.e. the same process as on Si. By analyzing the nearest neighbor distance distribution, we identify diffusion-induced repulsion of neighboring nanowires as the main mechanism limiting the nanowire number density during nucleation on TiN. Since on Si the final number density is determined by shadowing of the impinging molecular beams by existing nanowires, it is the difference in adatom surface diffusion that enables on TiN the formation of nanowire ensembles with reduced number density. These nanowire ensembles combine properties that make them a promising basis for the growth of core-shell heterostructures.

The final publication is available at link.springer.com

References in corpus (3)

• Self-regulated radius of spontaneously formed GaN nanowires in molecular beam epitaxy
• Correlation between the structural and optical properties of spontaneously formed GaN nanowires: a quantitative evaluation of the impact of nanowire coalescence
• Elastic vs. plastic strain relaxation in coalesced GaN nanowires: an x-ray diffraction study

Cited by in corpus (6)

• External control of GaN band bending using phosphonate self-assembled monolayers
• Growth kinetics and substrate stability during high-temperature molecular beam epitaxy of AlN nanowires
• Growth mechanisms in molecular beam epitaxy for GaN-(In,Ga)N core-shell nanowires emitting in the green spectral range
• Sequential directional deposition of one-sided (In,Ga)N shells on GaN nanowires by molecular beam epitaxy
• Density control of GaN nanowires at the wafer scale using self-assembled SiN${}_x$ patches on sputtered TiN(111)
• X-ray scattering study of GaN nanowires grown on Ti/Al${}_2$O${}_3$ by molecular beam epitaxy