We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow β-Ga2O3 at a growth rate ∼1 µm/h with control silicon doping concentration from 5 × 1016 1019 cm−3. In S-MBE, pre-oxidized gallium in form molecular beam that is 99.98% Ga2O, i.e., suboxide, supplied. Directly supplying Ga2O surface bypasses rate-limiting first step two-step reaction mechanism involved by conventional MBE. As ...