The present invention relates to a device for data storage. In particular the invention relates to a single electron memory device utilizing multiple tunnel junctions, and arrays or matrixes of such devices. The data storage device according to the invention comprises at least one nanowhisker adapted to store a charge. Each of the nanowhiskers comprises a sequence of axial segments of materials of different band gaps, arranged to provide a sequence of conductive islands separated by tunnel barriers and a storage island arranged at one end of the conductive island/tunnel barrier sequence, whereby to provide a data storage capability. The number of conductive islands should preferably be between five and ten.