University of Arizona (Tucson, AZ) earned U.S. Patent 7,786,472 for a quantum interference effect transistor (QuIET).
According to inventors Charles Allen Stafford, David Michael Cardamone and Sumitendra Mazumdar the transistor is a molecular-based switching device that includes a method for controlling charge transport across a molecule.
The molecular-based switching device includes a molecule having first and second nodes in between which destructive quantum interference restricts electrical conduction from the first node to the second node in an off-state, a first electrode connected to the first node and configured to supply charge carriers to the first node, a second electrode connected to the second node and configured to remove the charge carriers from the second node, and a control element configured to reduce coherence in or alter charge transport paths between the first and second nodes so as to reduce existing destructive quantum interference and permit flow of the charge carriers from the first node to the second node.
The method applies an electric potential between the first and second electrodes, controls coherence in charge transport paths between the first and second nodes so as to maintain or reduce destructive interference between the first and second nodes of the molecule, and injects charge carriers from the first electrode into the first node and collects the charge carriers from the second node at the second electrode when the coherence is controlled to reduce destructive interference.
One problem for nanoscale device technologies is fanout; due to the need for intermediate current drive (e.g., amplifiers) in these nanoscale devices. One solution according to the QuIET transistor is to incorporate nanoscale devices onto a conventional transistor amplifier layout serving as the fabrication substrate and thus provide a "hybrid" device structure. After coating the conventional transistor amplifier layout with an insulating layer, the metal interconnect and molecular layers are fabricated on top, with input to the amplifiers made via holes. This configuration permits one to drive or input an internal signal anywhere in the array.