Supplemenrary Material

the details of the definitions of averaged strain, formation energy, planar charge difference and the projected density of states, along with the interfacial atoms properties, complete structure, charge difference, electrostatic potential, Bader charge distribution, core level alignment scheme, properties of β-Ga2O3(3-10)/diamond(111) interface and β-Ga2O3(100)A/H-diamond(100) interface, electron affinity, layer density of states and partial charge density of states calculations.