Waveform analysis of GaAs FET breakdown

Drain-gate breakdown of GaAs metal-semiconductor-field-effect transistors (MESFETs) was analyzed using high frequency waveform probing. Peak dmin-gate voltage was theoretically and experhentally found to be a determining breakdown factor. The impact ionization induced conduction component of the gate and drain current of pinched-off MESFET at RF was found to correspond to the dc breakdown currents. The transit time of 30 ps was obtained for the impact ionization generated electrons to travel from gate to drain. This yields the hot electron drift velocity of 4.3 X 10⁶ cm/s which is in good agreement with the published data.