AVS 51st International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS1-ThA

Paper NS1-ThA1
Single Electron Charging in Individual InAs Quantum Dot Observed by Nonconctact Atomic Force Microscopy

Thursday, November 18, 2004, 2:00 pm, Room 213C

Session: Nanoscale Imaging
Presenter: Y. Miyahara, McGill University, Canada
Authors: Y. Miyahara, McGill University, Canada
R. Stomp, McGill University, Canada
S. Schaer, McGill University, Canada
Q. Sun, McGill University, Canada
H. Guo, McGill University, Canada
S. Studenikin, National Research Council, Canada
P. Poole, National Research Council, Canada
A. Sachrajda, National Research Council, Canada
P. Grutter, McGill University, Canada
Correspondent: Click to Email
Understanding the electronic structure of quantum dots (QD) is not only important for application but also of great interest in fundamental physics. Although there have been a number of studies of electronic properties using mainly optical or capacitance spectroscopy techniques, investigating a single QD remains challenging because of the extremely small dot dimensions. Spectroscopic techniques based on scanning probe microscopy have been employed, in particular scanning tunneling spectroscopy (STS). In STS the acquired tunneling spectra feature the Coulomb staircase or/and the discrete energy states of the QD depending on the size of the QD and the tunneling barrier thickness. However, these measurements are limited to substrates with adequate conductivity since a measurable tunneling current of typically 1 pA or more is usually required. Here, we report the first successful observation of the Coulomb blockade effect by electrostatic force measurements. The main experimental features in the electrostatic force vs. the tip-substrate bias voltage curves agree well with a simple theory based on the semi-classical theory of the Coulomb blockade effect. Comparison of the experimental results with the model calculation will be made and the possibility to observe the discrete energy states will also be discussed. One of the important differences to STS is that there is no continuous current flowing in the system. As a consequence, this technique can detect single electron events. Furthermore, this implies that this technique can also be applied to the QDs embedded in other materials.