Epitaxial growth of β-Ga₂O₃ on (110) substrate by plasma-assisted molecular beam epitaxy

Epitaxial growth of β-Ga₂O₃ films on (110) substrates has been performed via plasma-assisted molecular beam epitaxy (PAMBE). The atomic force microscopy scan shows a very low root mean square roughness of 0.08 nm for the surface of the as-received (110) substrates. High-resolution x-ray diffraction measurements reveal a 2.5 nm/min growth rate of β-Ga₂O₃ films on (110) substrates for conventional PAMBE growth conditions (∼700 °C), which is comparable to that on (010) substrates. The surface morphology of β-Ga₂O₃ epitaxial films is smooth and has a similar dependence on Ga flux to (010) growth. However, the (110) plane does not have a tendency to show a well-defined step–terrace structure in spite of the appearance of (110) facets in the growth of (010) β-Ga₂O₃. Indium catalyzed growth was also demonstrated to improve the growth rate up to 4.5 nm/min and increase the maximum growth temperature up to 900 °C of (110) β-Ga₂O₃.