AVS 51st International Symposium
    Semiconductors Tuesday Sessions
       Session SC-TuA

Paper SC-TuA6
Gated Si/SiGe Quantum Dots with Low Charge Noise

Tuesday, November 16, 2004, 3:00 pm, Room 304C

Session: Semiconductor Heteroepitaxy and Nanostructures
Presenter: L.J. Klein, University of Wisconsin, Madison
Authors: L.J. Klein, University of Wisconsin, Madison
S. Goswami, University of Wisconsin, Madison
K.A. Slinker, University of Wisconsin, Madison
K.L.M. Lewis, University of Wisconsin, Madison
S.N. Coppersmith, University of Wisconsin, Madison
D.W. van der Weide, University of Wisconsin, Madison
M.A. Eriksson, University of Wisconsin, Madison
J.O. Chu, IBM, TJ Watson Research Center
J.A. Ott, IBM, TJ Watson Research Center
P.M. Mooney, IBM, TJ Watson Research Center
Correspondent: Click to Email
The stability and noise affecting single electron charging in quantum dots fabricated in a Si/SiGe heterostructure are investigated. Electron beam lithography and subsequent reactive ion etching are used to define the quantum dot. The dot potential and electron density are modified by laterally defined side gates in the plane of the dot. Low temperature measurements (0.2 K) show Coulomb blockade with a single electron charging energy of 4 meV. The long term stability of the Coulomb blockade oscillations is determined in part by the number and stability of electrons captured in trap states in the vicinity of the quantum dot. Motion of this trapped charge modifies the dot potential and is detected as discrete shifts in the Coulomb blockade peak positions. Thermally annealing the sample (400C in Ar) after reactive ion etching reduces the charge noise from such trap states, allowing the acquisition of stable Coulomb diamond data over several hours. Tunnel-coupled double quantum dots have been fabricated and measured using similar techniques. The potential application of such Si/SiGe quantum dots for spin based quantum computation is discussed.