A new quantum dot transistor

The authors propose and demonstrate a novel quantum dot transistor (QDT), which consists of a nanoscale dot-gate inside the gap of a split-gate. The dot-gate consists of an 80-nm-diameter metal dot in the middle of a 30-nm-wide metal wire; when positively biased, the gate creates a quantum box connected by two 1D wires beneath the gate. The negatively biased split-gate is used to change the Fermi level and therefore the electron concentration in the quantum box. The gates are fabricated on top of a delta -doped AlGaAs/GaAs heterostructure using electron-beam lithography followed by a lift-off of Ti/Au. As the dot-gate voltage was scanned from 0 to 160 mV with the split-gate voltage fixed at -0.5 V, four distinct oscillation peaks appeared in drain current at T=0.5 K.