Coulomb Blockade Oscillations, Tunneling and Electrons Transport Through Quantum Dots
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Date
2018-06-01
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Addis Ababa University
Abstract
In this thesis, we studied Coulomb blockade oscillations, tunneling and electrons
transport through a quantum dot. Coulomb blockade oscillations of the conductance
are a manifestation of single electron tunneling through a quantum dot. We focus on
the electron transport between the dot and source(drain). The model of the study is
the linear conductance capable of describing the basic Physics of electronics states in
the quantum dot. Using the master equation analytic expression for the current(I)
through the quantum dot was derived and obtain the linear conductance through the
dot which is de_ned as G = limV!0( I
V ) in the limit of in_nitely of small bias voltage.
We will distinguish three temperature regimes, e2
C _ KBT, the discreteness of the
charge cannot be discerned, _E _ KBT _ e2
C , the classical metallic Coulomb blockade
regime many levels are excited by thermal uctuations, and KBT _ _E _ e2
C ,
the quantum Coulomb blockade regime, a few levels participate in transport.
Finally, we have performed the numerical computation of electron transport through
the quantum dot. We present graphs of the results for using the equations that we
derive. The linear conductances are plotted as a function of the gate voltage. The
Coulomb blockade oscillations occur as the voltage on a nearby gate electrodes varied.
In the valleys, the conductance falls o_ exponentially as a function of the gate voltage.
Figures (4.1-4.8), are the result of the study. At some intermediate temperature, the
conductance shows one oscillation but vary for the positive and negative gate voltage.
At high temperature, no oscillation conductance and at low temperature conductance
oscillates for some appropriately chosen capacitance.
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Keywords
Linear Response Conductance, High Temperature Behavior, Low Temperature Behavoir