Suspended quantum point contact with triple channel selectively driven by side gates

Abstract

The experimental study of the suspended GaAs quantum point contact (QPC) equipped with in-plane side gates reveals that, under such conditions, the QPC constriction has an unusual triple-channel structure involving three conductive channels with the quantized conductance selectively driven by the gates. The analysis of capacitance coefficients and channel widths allows us to conclude that the channels are narrow, compared to the lithographic constriction of the QPC, and that two of the channels are located along the constriction edges, while the other one passes along the middle line. The suspended QPC with the selectively driven triple-channel structure represents a device with an enhanced functionality. The electrostatic mechanism of the channel formation, specific for trench-type suspended QPCs with side gates, is discussed.