Charge Imaging Electrons in Nanoscale Systems

Michigan State University, East Lansing MI

Investigators

Abstract

This individual investigator award supports a project that exploits a novel technique, charge accumulation imaging (CAI) to probe the quantum mechanics of nanoelectronic systems in GaAs-AlGaAs heterostructures. CAI is a scanning probe method that permits minute amounts of electrical charge to be resolved with high spatial resolution (about 50 nm) in a cryogenic environment. By probing the spatial characteristics of the ground state of the 2D electron system and the energy levels of coupled quantum dots, nanostructures with confinement in all three directions, the experiments probe the nature of electron-electron interactions, and their interplay with defects. In addition to the contributions to basic science, the graduate and undergraduate students who will perform this research will receive a valuable education in advanced scanning probe and surface science techniques. Moreover, we plan to construct an educational scanning probe microscope to be showcased in the Michigan State University Science Theatre. Understanding the nature of electrons confined inside semiconductors to nanometer lengths has become increasingly essential as integrated circuits continue to rapidly scale down in size. Advanced microscopic techniques sensitive to the electronic structure will likely play key roles in developing future nanoelectronic devices. This research applies such a technique, Charge Accumulation Imaging, to probe nanoscale electronic systems formed in the semiconductor GaAs. By mapping out the electric field emanating from the semiconductor's surface, the technique can resolve the behavior of electrons inside the nanosystem, despite the fact that it is buried beneath the surface. The goal of the project is to investigate the nature of interactions between electrons, and their interplay with defects and impurities within the semiconductor. The research provides a challenging training ground for graduate and undergraduate students, as they master advanced microscopy and semiconductor microfabrication techniques. Moreover, we plan to construct an educational scanning probe microscope to be showcased in the Michigan State University Science Theatre. This demonstration will literally bring a hands-on introduction to nanotechnology for students in grades 6-12.