Temperature dependence of liquid-gallium ordering on the surface of epitaxially grown GaN

Abstract

The three-dimensional ordering of the gallium (Ga) adlayers on GaN(0001) and (000 $\bar{1}$ ) surfaces was probed using in situ X-ray scattering under MBE conditions. An ordered bilayer of Ga forms on GaN(0001) but the ordering decreases at substrate temperatures of <450 °C, consistent with the mechanism of non-equilibrium epitaxial growth. Monolayer Ga that forms on GaN(000 $\bar{1}$ ) is laterally disordered and has no temperature dependence, along with droplets of excess Ga. The vertical and lateral B-factors for each Ga layer were confirmed using first-principles molecular dynamics calculations.

Keywords

• molecular beam epitaxy
• gallium nitride
• X-ray scattering
• ordering