Towards smooth (010) β-Ga2O3films homoepitaxially grown by plasma assisted molecular beam epitaxy: the impact of substrate offcut and metal-to-oxygen flux ratio

Smooth interfaces and surfaces are beneficial for most (opto)electronic devices that are based on thin films and their heterostructures. For example, smoother interfaces in (010) beta-Ga2O3/(AlxGa1-x)(2)O(3)heterostructures, whose roughness is ruled by that of the beta-Ga(2)O(3)layer, can enable higher mobility 2-dimensional electron gases by reducing interface roughness scattering. To this end we experimentally prove that a substrate offcut along the [001] direction allows to obtain smooth beta-Ga(2)O(3)layers in (010)-homoepitaxy under metal-rich deposition conditions. Applying In-mediated metal-exchange catalysis (MEXCAT) in molecular beam epitaxy at high substrate temperatures (T-g= 900 degrees C) we compare the morphology of layers grown on (010)-oriented substrates having different unintentional offcuts. The layer roughness is generally ruled by (i) the presence of (110)- and 10