An atomic-scale depiction of the SketchSET shows three wires (green bars) converging on the central island (center green area), which can house up to two electrons. Electrons tunnel from one wire to another through the island. Conditions on the third wire can result in distinct conductive properties. Credit: Jeremy Levy, Univ. of Pittsburgh.
Good news, Moore’s Law: You are still not extinct. A group of researchers recently announced the development of a single-electron transistor that is said to be the first of its type made entirely of oxide-based materials. Named SketchSET, the transistor device demonstrates an approach to making erasable electronics that require about one-thousandth the area used in Intel Pentium processors (i.e., at the 45 nanometer production node). Moreover, one of the researchers says it could lead to self-contained devices that can create, as needed, their own transistors as well as other electronic components and circuitry.
A news release from University of Pittsburgh describes the transistor as consisting of an island formation that can house up to two electrons. According to the release, “the number of electrons on the island, which can be only zero, one or two, results in distinct conductive properties. Wires extending from the transistor carry additional electrons across the island.”
This research, published in Nature Nanotechnology (doi:10.1038/nnano.2011.56), reports that the transistor’s central component, an “island” only 1.5 nanometers in diameter, operates with the addition of only one or two electrons. That capability would make the transistor important to a range of computational applications, from “ultradense nonvolatile memories, nanoscale hybrid piezoelectric and charge sensors as well as building blocks in quantum information processing and simulation platforms.”
According to the Pitt release, the tiny central island also could be used as an “artificial atom” for developing new classes of artificial electronic materials, such as exotic superconductors with properties not found in natural materials.
The lead researcher, Jeremy Levy, is a professor of physics and astronomy at the University of Pittsburgh and a member of The American Ceramic Society. Other institutions involved in the research include Laboratório Nacional de Luz Síncrotron, Brazil; Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas-UNICAMP, Brazil; University of Wisconsin–Madison’s Department of Materials Science and Engineering; and Hewlett Packard Laboratories.
Short for “sketch-based single-electron transistor,” SketchSET’s name was reportedly coined by Levy because the technique works like a microscopic Etch A Sketch, the drawing toy of Levy’s youth that inspired his idea. The technique was originally developed in 2008.
Levy’s group leverages the properties they find at the interface between a crystal of strontium titanate and a 1.2 nanometer layer of lanthanum aluminate. Using the conducting probe of an atomic force microscope, they can precisely and reversibly toggle the metal–conductor transition in desired regions at the SrTiO3–LaAlO3 interface. They then use these techniques to create wires and transistors of nanometer dimensions. Explicit in this is another important characteristic: These electronic devices can then be “erased,” and the interface can be used over again.
This work could represent a disruptive technology, in terms of how electronic devices are fabricated. Levy says in a brief video on this topic (see below) that this work technology could create a stark alternative to the current chip fabrication systems. He says instead of enormous chip fab plants, “In principle, what we are doing can be scaled down to the size of the object in which that system we create — the transistor system — would reside. So, in fact, you might imagine putting all the capabilities required to create these structures within the object, itself, something on the size of an (Apple) iPod Nano.”
The group’s research is supported in part by grants from DARPA, the Army Research Office, NSF and the Fine Foundation.
In addition to this research, Levy is also leading a $7.5 million, multi-institutional project to construct a semiconductor with properties similar to SketchSET. This five-year project is intended to overcome some of the most significant challenges related to the development of quantum information technology. Levy is working on this project with researchers from Cornell University, Stanford University, University of Michigan, University of Wisconsin–Madison and University of California, Santa Barbara. This project began in August 2010 and is funded by the Air Force Office of Scientific Research’s Multi-University Research Initiative.