Fabrication and characterisation of Coulomb blockade devices in silicon

Silicon Coulomb blockade structures have been fabricated from silicon on insulator substrates and electrically characterised. The devices were realized as a single Si island connected to two electron reservoirs by Si tunnelling barriers. The silicon base substrate served as a backgate. Clear Coulomb blockade behaviour in the I(V) characteristics was observed at temperatures up to 110K with a large Coulomb gap of 1Volt at zero backgate voltage. The Coulomb gap was found to be strongly dependent on the backgate voltage. Periodic source-drain current oscillations were measured at 4.2K by sweeping the backgate voltage. The geometrical and the electrical shape of the device were found to be different. Despite the designed two tunnelling barriers and a single dot the observed electrical behaviour can only be explained by the assumption of multiple tunnel junctions.