A strong negative transconductance is investigated in in-plane-gate transistors written by focused-ion-beam implantation in the two-dimensional electron gas in modulation-doped AlGaAs/GaAs heterostructures. This occurs in a configuration where two in-plane gates G1 and G2 used to control the current through a channel lying between them are biased with different voltages V g1 and Vg2. When the voltage Vg2<0 is held constant, the current through the channel can be reduced to zero by increasing Vg1 beyond a critical value. In an earlier study this effect was attributed to velocity modulation. It is found, however, that in this regime Vg1 causes a very small current Ig2 to flow across gate G2. It is observed that changes in Id are correlated to changes in Ig2 and thus conclude that Ig2 is responsible for the strong negative transconductance.
ASJC Scopus subject areas
- Physics and Astronomy(all)