X-ray scattering study of GaN nanowires grown on Ti/Al${}_2$O${}_3$ by molecular beam epitaxy

Abstract

GaN nanowires (NWs) grown by molecular beam epitaxy on Ti films sputtered on Al${}_2$O${}_3$ are studied by X-ray diffraction (XRD) and grazing incidence small-angle X-ray scattering (GISAXS). XRD, performed both in symmetric Bragg reflection and at grazing incidence, reveals Ti, Ti${}_3$O, Ti${}_3$Al, and TiO${}_x$N${}_y$ crystallites with in-plane and out-of-plane lattice parameters intermediate between those of Al${}_2$O${}_3$ and GaN. These topotaxial crystallites in Ti film, formed due to interfacial reactions and N exposure, possess fairly little misorientation with respect to Al${}_2$O${}_3$. As a result, GaN NWs grow on the top TiN layer possessing a high degree of epitaxial orientation with respect to the substrate. The measured GISAXS intensity distributions are modeled by the Monte Carlo method taking into account the orientational distributions of NWs, a variety of their cross-sectional shapes and sizes, and roughness of their side facets. The cross-sectional size distributions of the NWs and the relative fractions of $(1\bar{1}00)$ and $(11\bar{2}0)$ side facets are determined.

References in corpus (3)

• A growth diagram for plasma-assisted molecular beam epitaxy of GaN nanocolumns on Si(111)
• Correlation between the structural and optical properties of spontaneously formed GaN nanowires: a quantitative evaluation of the impact of nanowire coalescence
• Self-Assembled formation of long, thin, and uncoalesced GaN nanowires on crystalline TiN films

Cited by in corpus (1)

• Density control of GaN nanowires at the wafer scale using self-assembled SiN${}_x$ patches on sputtered TiN(111)