Suppression of tunnelling because adding or removing a discrete island charge costs more energy than the accessible transport and thermal energy window. Weak junction coupling and small island capacitance make it observable.
A higher-order tunnelling process through intermediate virtual charge states. It can produce transport inside a region where sequential first-order tunnelling is suppressed by Coulomb blockade. Its relevance grows as junction coupling increases.
The electrostatic scale for placing one elementary charge on a capacitance , conventionally . The discrete second difference of the quadratic island energy is , which is the charging contribution to successive-electron addition energies. State the convention when comparing numerical values.
A model with charge-independent total capacitance and a separate single-particle orbital spectrum. An addition energy is , whereas the conventional electrostatic charging scale is . The factor of two should not be confused with diamond full height.
With , the addition electrochemical potential is . Gate and lead voltages enter . Adjacent addition potentials differ by an orbital spacing plus .
A blocked region in a source-drain-voltage versus gate-voltage diagram of a small charge island. Gate widths, edge slopes and tip heights encode gate coupling, junction capacitance ratios and addition energies; extracting named source/drain values requires a bias convention.
With source biased and drain grounded, a constant-interaction island has diamond edge slopes and . The latter includes the gate capacitance. A gate period for charging without an orbital gap is . Combining widths and slopes determines capacitances only under a stated bias and single-island model; shell gaps must not be mistaken for a universal gate period.
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Coulomb blockade is a quantum mechanical phenomenon that occurs in small conductive structures, such as small metal or semiconductor particles (quantum dots) or single-electron transistors. It is characterized by the suppression of electrical conduction due to the electrostatic repulsion between charged particles—specifically, electrons. In a typical scenario, when an electron is added to a small conductor, it experiences a Coulomb energy barrier due to the presence of other electrons already in the conductor.