This research project seeks to understand the basic operating principle behind a newly discovered method for fabricating circuits whose size approaches atomic-scale dimensions. Current computer technology is based on silicon transistors which are getting close to their smallest possible size. Oxide nanoelectronics offers a new way to create transistors and other circuit elements that are required for information technology, but many basic properties are still not well understood. One way of developing such an understanding is to use a technique called atomic force microscopy, in which a small needle-like probe is scanned over a surface to measure the shape as well as alter the properties by using applied voltages to the probe. This research project will use an extension of the capabilities of such an instrument to allow the properties to be measured at much lower temperatures than was previously possible. Such control will help to uncover some of the basic mechanisms for writing and erasing nanoscale transistors and other devices. The project will provide formative experiences for the graduate student involved in the project. The low-temperature images are likely to create appealing visual representations of these nanostructures, ones that will appeal to young, impressionable students choosing their future academic trajectories.
TECHNICAL DETAILS A novel method for writing and modifying conducting nanostructures at the interface between two insulators (LaAlO3 and SrTiO3) has been invented by the PI. This project will extend the operating range of a vacuum atomic force microscope (AFM) so that oxide nanostructures can be cooled to 4 K while being probed by a conducting AFM tip. At low temperatures, thermal activation of carriers from donor site is suppressed, revealing the underlying potential produced by the AFM writing process. The tip will act like a local gate, enabling the nanostructure to be probed locally and in situ, and for the potential profile to be mapping with high spatial resolution. The extended temperature range (the instrument currently operates only down to 130 K) will allow feedback on the device structure in real time so that exotic quantum states can be defined at temperatures where transport measurements are made.
