Imaging a Coupled Quantum Dot - Quantum Point Contact System

Abstract

We performed measurements on a quantum dot and a capacitively coupled quantum point contact by using the sharp metallic tip of a low-temperature scanning force microscope as a scanned gate. The quantum point contact served as a detector for charges on the dot or nearby. It allowed us to distinguish single electron charging events in several charge traps from charging events on the dot. We analyzed the tip-induced potential quantitatively and found its shape to be independent of the voltage applied to the tip within a certain range of parameters. We estimate that the trap density is below 0.1% of the doping density and that the interaction energy between the quantum dot and a trap is a significant portion of the dot's charging energy. Possibly, such charge traps are the reason for frequently observed parametric charge rearrangements.

6 pages, 5 figures

References in corpus (3)

• Spatially resolved manipulation of single electrons in quantum dots using a scanned probe
• Imaging a Single-Electron Quantum Dot
• Single electron charging of impurity sites visualized by scanning gate experiments on a quantum point contact

Cited by in corpus (10)

• Electron counting in quantum dots
• On the imaging of electron transport in semiconductor quantum structures by scanning-gate microscopy: successes and limitations
• Interference of electrons in backscattering through a quantum point contact
• Ultra-shallow quantum dots in an undoped GaAs/AlGaAs 2D electron gas
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• Imaging Electron Motion in Graphene
• Formation of quantum dots in the potential fluctuations of InGaAs heterostructures probed by scanning gate microscopy
• Electron backscattering in a cavity: ballistic and coherent effects
• Supercurrent modulation in InSb nanoflag-based Josephson junctions by scanning gate microscopy
• Signatures of Majorana bound states in scanning gate microscopy of hybrid nanowires