Modelling of structural and threshold voltage characteristics of randomly doped silicon nanowires in the Coulomb-blockade regime

We report on the theoretical investigation of how geometrically uniform highly doped silicon nanowires can break up into a series of islands that exhibit Coulomb blockade. By using a newly developed numerical simulation in which random ionized dopants are introduced explicitly and the electron distribution is calculated self-consistently under the Thomas-Fermi approximation, we demonstrate natural formation of electron islands in the nanowires owing to the random dopant potential. We study the quasi-one-dimensional nature of the electron islands formed in the nanowires. The offset charge effects on the current threshold of the nanowire transistors are then investigated by feeding the derived structural parameters such as inter-island capacitance and tunnel resistance into a Monte Carlo single electron transport simulator. We show that the overall threshold voltage distribution can roughly be described as a two-'macro'-island system despite a complex series of multiple electron islands.