Monte Carlo simulation of the growth of metallic quantum dots

Abstract

The phenomenon of Coulomb Blockade allows to control the flow of individual electrons and has raised hopes of building electronics devices based on such phenomenon. In order to observe Coulomb Blockade, islands, or dots, on the nanometre scale must be fabricated in order to obtain a small enough capacitance for the electrostatic energy associated with adding a single electron to the island to exceed thermal fluctuations. Coulomb Blockade has been observed both in semiconductor and in metallic structures. In particular irregular 2D arrays of metallic dots of typical size less than 10nm have been fabricated by means of Electron Beam Lithography combined with granular film deposition. In this paper we present a theoretical study of the grain deposition and subsequent island formation based on a Monte Carlo technique. The model allows to account for a variety of important parameters such as temperature, diffusion vs. deposition rate, and in particular the effect of contacts. Optimum parameters to obtain reproducible Coulomb Blockade devices are suggested.