Electron transport in single-walled carbon nanotube nanostructured devices

Abstract

Single-electron pump (SEP) devices that can deliver single electrons at high frequencies are fabricated using two different gate geometries. The pump quantum dot (QD) can be defined either using two finger gates where the pump operates in what is known as the conventional pumping regime (CPR), or alternatively, the QD can be designed with the use of a single finger gate and split gate, where the pump operates in the long pumping regime (LPR). Here we investigate pump maps produced in both the CPR and LPR under the affects of a low magnetic field (1 T to -1 T) and observe both the evolution of the pump map and pump accuracy. Measurements were carried out in a cryogen-free dilution refrigeration system with the use of a superconducting magnetic. Clear discrepancies between the behaviour of measured current can be seen, indicating a fundamental difference in the operation of the pumps in the two different pumping regimes.