AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS+EM-TuM

Paper NS+EM-TuM4
Top-gated Quantum Dots in Silicon / Silicon-Germanium Two-Dimensional Electron Gases

Tuesday, November 1, 2005, 9:20 am, Room 210

Session: Nanoscale Electronic Devices & Detection
Presenter: K.A. Slinker, University of Wisconsin - Madison
Authors: K.A. Slinker, University of Wisconsin - Madison
L. McGuire, University of Wisconsin - Madison
K.L.M. Lewis, University of Wisconsin - Madison
C.C. Haselby, University of Wisconsin - Madison
S. Goswami, University of Wisconsin - Madison
L.J. Klein, University of Wisconsin - Madison
J.O. Chu, IBM Research Division, T. J. Watson Center
M. Friesen, University of Wisconsin - Madison
M.A. Eriksson, University of Wisconsin - Madison
Correspondent: Click to Email
Electrons in silicon/silicon-germanium two-dimensional electron gas (2DEG) quantum dots are a promising architecture for spin based quantum computation. Schottky gated quantum dots allow precise tuning of electron shape and interdot coupling; however, up until now top gates on Si/SiGe heterostructures have not been used to deplete into the tunneling regime, most likely due to problems with gate leakage. We have overcome these problems by reducing the active 2DEG area into sub-micron mesas and back gating the 2DEG to tune the carrier concentration to be depleted by the top gates. We report on the depletion characteristics of these Schottky gates as well as successful Si/SiGe quantum dot architectures incorporating top gates. For one quantum dot device, an 800 nm channel is fabricated by electron beam lithography and subsequent reactive ion etching. Metal gates are deposited across the channel to define the leads of the dot, and an etch-defined side gate is used to vary the potential in the dot. The sides of dot are defined by surface depletion from the etched sidewalls. In another device, six metal gates are used to electrostatically define the dot on all sides - a set of pincher gates on each lead and two plunger gates. Properties of the dots are presented and compared.