Catalyst-Assisted Large-Area Growth of Single-Crystal β-Ga ₂O ₃ Nanowires on Sapphire Substrates by Metal–Organic Chemical Vapor Deposition

Abstract

In this work, we have achieved synthesizing large-area high-density β-Ga ₂O ₃ nanowires on c-plane sapphire substrate by metal–organic chemical vapor deposition assisted with Au nanocrystal seeds as catalysts. These nanowires exhibit one-dimensional structures with Au nanoparticles on the top of the nanowires with lengths exceeding 6 μm and diameters ranging from ~50 to ~200 nm. The β-Ga ₂O ₃ nanowires consist of a single-crystal monoclinic structure, which exhibits strong ( $\overline{2}$ 01) orientation, confirmed by transmission electronic microscopy and X-ray diffraction analysis. The PL spectrum obtained from these β-Ga ₂O ₃ nanowires exhibits strong emissions centered at ~360 and ~410 nm, respectively. The energy band gap of the β-Ga ₂O ₃ nanowires is estimated to be ~4.7 eV based on an optical transmission test. A possible mechanism for the growth of β-Ga ₂O ₃ nanowires is also presented.