ABSTRACT
The trend toward the reduction of device dimensions has found a severe limitation in impact ionization phenomena. The high fields occurring in the region under the drain edge of the gate of submicron FET devices cause carrier multiplication. Most of the generated holes are collected at the gate electrode, accounting for the sudden increase in the gate current that can be observed as the drain potential overcomes a certain threshold. This chapter reports measured gate current vs source potential curves for GaAs MESFETs showing the same bell shape found in Si MOSFET samples for substrate current. Measurements of gate current performed on GaAs MESFETs, where at sufficently high drain bias the main contribution to Ig has been shown to come from impact-ionization-generated holes collected at the gate electrode, show a bell-shape dependence on gate potential.
