Ozone-Enhanced Molecular Beam Epitaxy

Abstract

This chapter explains homoepitaxial growth of β-Ga₂O₃ by using ozone-enhanced molecular beam epitaxy (MBE). First, in order to reveal the suitable surface orientation for β-Ga₂O₃ homoepitaxial MBE growth, we investigate the surface orientation dependence of the growth rate and surface morphology. The results show that the (010) plane is the most suitable one for growth. Next, we optimize the growth conditions of films grown on the (010) plane. In the case of unintentionally doped films, we find that smooth surface films can be obtained by optimization of the surface migration of Ga and O adatoms. On the other hand, in the case of Sn-doped films, segregation of Sn leads to roughening of the surface. A highly O-rich condition is good for obtaining a smooth surface, because it reduces segregation of Sn. By optimizing the growth conditions in this manner, one can fabricate device-quality β-Ga₂O₃ homoepitaxial films with precisely controllable donor concentrations over a wide range (10¹⁶–10¹⁸ cm⁻³) and atomically flat surfaces.