Current-controlled negative differential resistance in four-terminal heterostructure devices

Abstract

We demonstrate new effects of the current-controlled (S-shaped) negative differential resistance (NDR) in different circuit configurations of four-terminal modulation-doped AlGaAs/GaAs heterostructure devices, with the magnitude of the voltage drop varied by external electrodes. We observe two S-shaped instabilities having different physical origins. One effect arises due to an avalanche in the top AlGaAs layer underneath the reverse-biased gate region. Another phenomenon relies on the creation, during the avalanche, of nonequilibrium hot electrons at the conducting channel (quantum well). This dramatically enhances electron flow over the heterostructure barriers and gives rise to a strongly pronounced current-controlled NDR with a peak-to-valley ratio of ∼10.