Modelling of impedance dispersion in lateral β-Ga₂O₃ MOSFETs due to parallel conductive Si-accumulation layer

Frequency dispersion of impedance in lateral β-Ga₂O₃ MOSFETs has been characterized and a model has been established to explain the behavior. The dispersion occurs due to resistive and capacitive coupling between terminal contact pads and the buried conducting layer associated with the accumulation of Si contaminant at the unintentionally-doped epitaxy/substrate interface, which is also responsible for a buried parallel leakage path. Particularly, it is demonstrated that the dispersion is not associated with gate dielectric traps as would often be assumed. A generalized equivalent circuit model, which is capable of reproducing the experimental results, is proposed to explain the observations.