Modulation of Drain Current by Holes Generated by Impact Ionization in GaAs MESFET

A hole current generated by impact ionization in the channel at high drain voltages is measured using a GaAs MESFET with a conductive buried p layer (CBP-MESFET). The hole injection into the p layer beneath the channel is found to be the origin of the kink effect. A sidegating effect in the CBP-MESFET is also studied. A suppression of the sidegating effect by the negatively biased p layer is shown. An anomolous behavior in the sidegating effect at high drain voltages is observed; it may be related to the holes generated by impact ionization.