Aperture-limited conduction and its possible mechanism in ion-implanted current aperture vertical β-Ga2O3 MOSFETs

An anomalous diode-like turn-on behavior was observed in the drain characteristics of current aperture vertical β-Ga2O3 transistors. This phenomenon was attributable to an electron barrier created by negative fixed charges in the aperture opening, through which electrons were funneled from the gated channel to the drift layer. Electrostatic analysis for deriving the turn-on voltage yielded effective sheet charge densities on the order of 1011–1012 cm−2. The charged species was conjectured to be acceptor-like point defects diffusing from nitrogen-implanted current blocking layers with an activation energy consistent with migration of gallium vacancies. These results alluded to a possible role of point-defect diffusion in the performance and reliability of ion-implanted Ga2O3 devices.