Quantum Transport in InAs Nanowires with Etched Constrictions and Local Side-gating

To study transport properties in single InAs nanowires (NW) with etched constrictions, a bunch of back-gated single InAs NW devices were made. The standard device contained a NW section with an etched constriction, placed between two pre-patterned side-gates. For comparison, devices either without etched constriction or without side-gates were also fabricated. Transport measurement results of three devices were presented and discussed. The device without side-gates exhibited Coulomb blockade due to electron tunneling through double quantum dots (QDs). The device without the etched constriction displayed conductance quantization. The standard device showed both Coulomb blockade (due to electron tunneling through either multiple QDs or single QD) and Fabry-Perot conductance oscillation at different gate bias regime. A 3-D electrostatic and 2-D eigenvalue coupled simulation was conducted to explain the observed conductance quantization. This model suggests that the nonuniform potential distribution in a thick NW dramatically modifies the confinement energies in the NW.MAS