Any future quantum standard of current requires that the transport of individual electrons can be controlled precisely. One potential approach relies on single electron tunnelling through very small nano-islands which due to their size provide only one state for the tunnelling electron.

In this project special nano islands made of Indium Arsenide are produced and studied. The so-called Indium Arsenide quantum dots are grown in a special growth system (molecular beam epitaxy) and are already during the growth embedded in suitable semiconductor material of different composition.

Up to now the growth conditions have been optimised and the structural and other properties of the quantum dots, when embedded in the barrier material Aluminium Arsenide, have been studied. Resonant tunnel diodes containing ensembles of quantum dots exhibited current-voltage characteristics with well resolved steps which are due to resonant tunnelling through individual dots. First experiments on tunnelling through vertically stacked dots show interesting effects related to the coupling of the two nano islands.

In order to achieve a well controlled tunnel current the resonant tunnel diodes will in the next step be miniaturised in order to address the individual quantum dots and to cycle the single charges with an additional gate electrode.