NER: Caged Clusters for Single-Electronics

This Nanoscale Exploratory Research (NER) proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 02-148). The project addresses synthesis and processing of cluster based hybrid molecular-electronic architectures to overcome fundamental limits to miniaturization of solid state semiconductor mass-produced circuitry. Emphasis is on control of precise composition and the spatial arrangement of clusters. Part of the motivation for the project is that it may be possible to arrange groups of clusters so that they perform the basic functions of electronic circuits, with the presence or absence of single electrons representing bits of information. A cluster-based single-electronics technology could provide a means to overcome the technical and fundamental barriers that are expected to limit further miniaturization of current types of electronic circuit, but also set the stage for the implementation of revolutionary electronic circuit designs based on the principles of single-electronics. Preliminary studies have shown that even networks with relatively simple single-electron synapses could be sufficiently complex to reproduce some of the characteristic capabilities of the human brain. Thus extremely powerful signal processing technologies may become available in the foreseeable future. In this exploratory project molecular frameworks of sufficient size to enclose clusters will be synthesized. Initially, the frameworks will be modified by means of appended side chains to fulfill two tasks: hold clusters with diameters of up to 2 nm and mediate the attachment of "caged clusters" to solid surfaces. The electron transport properties of these caged clusters will then be studied. In subsequent work, the frameworks will be interconnected to form precisely defined cluster arrays that function as single-electron devices. Additionally, they will be interfaced with nanofabricated electronic circuits to demonstrate the feasibility of novel computing architectures based on principles of single-electronics. The proposed research is a collaborative effort involving researchers from two Departments (Chemistry; Physics and Astronomy). %%% The project addresses basic exploratory research issues in a topical area of materials science and chemistry with high technological relevance; it is considered a high risk/high pay-off activity. The project encompasses the NSE research and education theme of Nanoscale Structures, Novel Phenomena, and Quantum Control. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. The scope of the project is interdisciplinary, spanning atom-by-atom construction and physical characterization of nanostructures to the integration of such structures with existing technology. This interdisciplinary research setting is expected to attract students to nanoscience and provide a unique training ground for young scientists at all stages of their education and training. The research results will be published in scientific journals, and also used to attract local undergraduate and high school students into research activities. The project is jointly supported by the MPS/DMR/EM and the MPS/CHE Special Projects and IBO programs.