Abrupt negative differential resistance in ungated GaAs FET's

We report on an investigation of an abrupt negative differential resistance (NDR) observed in the I-V characteristics of ungated GaAs FET's with submicron gate recess trenches. The NDR is a sensitive function of drain voltage, and its magnitude on the current axis and position on the voltage axis are functions of gate recess depth. The effect is attributed to fast intervalley scattering because of a modified electric field as etching proceeds, and it is possible that it can be used to implement high-speed logic circuits.