Fig. 1: Schematic plot of the bilayer β-Ga2O3 and β-Ga2O3’s frequency-dispersive permittivity.

a Twisted stacks of β-Ga2O3 with a thickness of d. The superstrate and substrate are air. Direction [001] is within the x-y plane but is not orthogonal to the x-axis [001]. b The components of permittivity tensor of β-Ga2O3.