Batch of 12 single electron devices on a GaAs substrate The aim of this work package is to develop a reliable and diverse supply line for at least 7 types of single-electron current sources, consistent with the vision of an SI system based on fundamental constants of nature. The fastest and most accurate pumping has been achieved using so-called ‘tuneable-barrier’ pumps made from semiconductors gallium arsenide (GaAs) and silicon (Si). Single electron pumps in two material systems, GaAs (left) and Silicon (right) This project will focus on these two materials and will mostly concentrate on improving proven fabrication processes, which have already demonstrated a high yield of working devices. In order to maximise the output currents, up to 6 GaAs single-electron sources will be parallelised. A novel type of device structure, where a two-dimensional array of single-electron sources are controlled by an on-chip multiplexer technology, will also be developed.