Parasitic bipolar effects in submicrometer GaAs MESFET´s

We report the observation for the first time of parasitic bipolar action in GaAs MESFET´s. It manifests itself in the form of increased transconductance at higher drain voltage, abrupt change in output conductance (kink effect) around 4-V drain-source voltage, and a gate-voltage-dependent substrate current. These effects are explained by electron-hole pair generation in the high-field region at the drain. The holes generated are injected into the substrate where they form the base region of a parasitic lateral bipolar transistor. The effect also explains a new breakdown mechanism for short-channel enhancement-mode MESFET´s.