Anomalous gate-to-drain capacitance characteristics of GaAs MESFET´s

Anomalous gate-to-drain capacitance characteristics of GaAs MESFET´s are discussed using a two-dimensional device simulator. Gate-to-drain capacitance CGDshows sharp undershoot characteristics with an increase in drain-to-source voltage VDSfor a large donor concentration-thickness product device having a negative drain conductance. By analyzing the distribution of carrier variation against a small gate-to-drain voltage change, it is found that the CGDundershoot occurs due to a stationary domain formation at the drain side under the gate. The condition for the domain formation is also discussed to clarify the anomaly in CGD.