2009/09/30 by Lynda Cockins, Yoichi Miyahara, Steven Bennett +8 · 2 citations
Physics and Astronomy · #Force Microscopy Techniques and Applications #Mechanical and Optical Resonators #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1073/pnas.0912716107
published as PNAS, 107 9496-9501 (2010) · 11 pages, 6 figures
arxiv created 2009/09/30 · openalex publication_date 2010/05/08 · arxiv updated 2010/06/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Strong confinement of charges in few-electron systems such as in atoms, molecules, and quantum dots leads to a spectrum of discrete energy levels often shared by several degenerate states. Because the electronic structure is key to understanding their chemical properties, methods that probe these energy levels in situ are important. We show how electrostatic force detection using atomic force microscopy reveals the electronic structure of individual and coupled self-assembled quantum dots. An electron addition spectrum results from a change in cantilever resonance frequency and dissipation when an electron tunnels on/off a dot. The spectra show clear level degeneracies in isolated quantum dots, supported by the quantitative measurement of predicted temperature-dependent shifts of Coulomb blockade peaks. Scanning the surface shows that several quantum dots may reside on what topographically appears to be just one. Relative coupling strengths can be estimated from these images of grouped coupled dots.