Excited-state spectroscopy on an individual quantum dot using atomic force microscopy.
We present a new charge sensing technique for the excited-state spectroscopy of individual quantum dots, which requires no patterned electrodes. An oscillating atomic force microscope cantilever is used as a movable charge sensor as well as gate to measure the single-electron tunneling between an individual self-assembled InAs quantum dot and back electrode. A set of cantilever dissipation versus bias voltage curves measured at different cantilever oscillation amplitudes forms a diagram analogous to the Coulomb diamond usually measured with transport measurements. The excited-state levels as well as the electron addition spectrum can be obtained from the diagram. In addition, a signature which can result from inelastic tunneling by phonon emission or a peak in the density of states of the electrode is also observed, which demonstrates the versatility of the technique.
Department of Physics, McGill University, 3600 rue University, Montreal, Quebec H3A2T8, Canada.
Lynda
L
Cockins
Yoichi
Y
Miyahara
Steven D
SD
Bennett
Aashish A
AA
Clerk
Peter
P
Grutter
D004566:Electrodes; D018625:Microscopy, Atomic Force / Q000379:methods*; D045663:Quantum Dots