KINK EFFECT RELATED TO THE SELF-SIDE-GATING EFFECT IN GAAS-MESFETS

A kink effect, an abrupt increase in drain current at high drain volta ges, was observed in GaAs MESFET's with an Al0.2Ga0.8AS/GaAs heterostr ucture buffer layer. In these MESFET's, impact ionization occurs at th e drain side along the channel current path at high drain voltages. On the other hand, a side-gating effect occurs when a negative voltage a pplied to the gate pad of the MESFET (self-side-gating effect). From m easurements of the substrate potential, we conclude that hole accumula tion generated by the impact ionization at the channel-side GaAs/Al0.2 Ga0.8As interface cancels the drain current reduction that arises from the self-side-gating effect. This gives rise to the kink effect we ob serve.