Large threshold hysteresis in a narrow AlGaAs/GaAs channel with embedded quantum dots

Self-assembled InGaAs quantum dots have been grown by molecular-beam epitaxy in the spacer of AlGaAs/GaAs modulation-doped heterostructures. The wafer has been further processed by electron-beam lithography and etching techniques in order to realize 70 nm wide channels controlled by lateral side gates. It is found that the drain current threshold differs by up to 2 V with respect to down and up sweeps of the gate voltage. The large hysteresis is attributed to charging and discharging of the quantum dots in the spacer and persists up to 260 K.