Chloride epitaxy of $\beta$-Ga$_{2}$O$_{3}$ layers grown on $c$-sapphire substrates

The method of chloride epitaxy is employed to grow $\beta$-Ga$_{2}$O$_{3}$ epitaxial layers on a $c$-sapphire substrate. Purified dry air is used as the source of oxygen. The layers are studied using the methods of X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and micro-Raman spectroscopy. It is found that the growth plane of the layers is ($\bar2$01), parallel to the substrate surface. The layers consist of separate large crystalline grains of three different in-plane orientations rotated relative to each other in the growth plane by 60$^\circ$. Misorientation can be caused by the different symmetry of the substrate and the epitaxial layer.