Epitaxial relationship between wurtzite GaN and β-Ga2O3

The epitaxial relationship between wurtzite GaN and monoclinic $\beta \text{-}{\mathrm{Ga}}_2{\mathrm{O}}_3$ is studied by transmission electron microscopy. GaN is grown on $\beta \text{-}{\mathrm{Ga}}_2{\mathrm{O}}_3$ by molecular beam epitaxy without any low-temperature buffer layer, obtaining $c$ plane GaN on $a$ plane $\beta \text{-}{\mathrm{Ga}}_2{\mathrm{O}}_3$ . The effect of the surface nitridation, which is necessary for the epitaxial growth, is analyzed at the atomic level. The lattice mismatch has a minimum of 2.6% for the in-plane epitaxial relationship ${⟨011⟩}_{{\mathrm{Ga}}_2{\mathrm{O}}_3}\Vert {⟨10\overline{1}0⟩}_{\mathrm{Ga}\mathrm{N}}$ .