Abstract
Using frequency dependent capacitance spectroscopy the dynamics of tunnelling is investigated from a three-dimensional back contact into ensembles of self assembled InAs quantum dots. An equivalent RC circuit is derived from the balance of charge which allows the charging time for each state of the dots to be determined. This method is applied to investigate the charging dynamics of samples with double layers of vertically aligned InAs quantum dots. In these structures the interplay between Coulomb blockade effects and sequential tunnelling can be seen: The tunnelling probability for the dots in the second layer is either increased by sequential tunnelling through states of the first dot layer or reduced by Coulomb blockade effects.
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