Random Background Charges
The most serious deficiency with single-electronics is the so-called random background charge problem. Quantum dots are highly susceptible to nearby charges which can stem from several sources: charged impurities in the surrounding material, charged traps on surfaces and grain boundaries, charges on nearby conductors, and ionizing radiation. On top of that, these background charges will be in general mobile and move and change over time. Thus in both, space and time, we have to deal with random background charges. These random charges are so devastating, because they can fully suppress the Coulomb blockade, which is equivalent with a destruction of intended device behavior. As a simple example let us take a look at the Coulomb blockade dependence on background charge for a single-electron transistor. Figure 120 shows the I – V characteristic for a symmetrically biased SET for three different background charges.
KeywordsBias Voltage Tunnel Junction Tunnel Barrier Coulomb Blockade Background Charge
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