Power gain up to gigahertz frequencies in three-terminal nanojunctions at room temperature

Direct current and alternating current characteristics of three-terminal nanojunctions (TTJs) are studied at room temperature. The TTJs are based on a modulation-doped GaAs/AlGaAs heterostructure and were structured by applying mask techniques and wet chemical etching. Devices with lateral dimensions of a few tens of nanometers and with narrow gold contacts were fabricated and transistor characteristics with maximum transconductance values exceeding 100 mu A/V are demonstrated. By analyzing the scattering parameters of the TTJs, power gain up to 1.5 GHz is observed. This gigahertz amplification is related to the implemented narrow gold contacts which control the quantum capacitance of the electron reservoirs.