Coulomb blockade theory applied to semiconductor nano-structures: modeling of nano-crystal silicon devices

The current breakthroughs in semiconductor nano-structure fabrication allows the emergence of innovative device concepts based on quantum mechanics as alternative to conventional CMOS transistors or memories. Among other things, the Coulomb blockade devices like single-electron transistors offer one of the most promising prospects. The modeling and simulation of single-electron structures are thus of first importance with a view to predicting and understanding the behavior of these new generation devices. In this context, this work is dedicated to the study of silicon quantum dots for Coulomb blockade applications. First, after having presented the state of the art, both theoretical and experimental, of Coulomb blockade devices, we are interested in the electronic structure of semiconductor quantum dots surrounded by silicon dioxide. This study leads us to develop a series of models for unbiased and biased quantum dots and, especially, a one-dimensional one able to describe spherically symmetric quantum dots within considerably reduced computation time. Moreover, the limitations of the effective mass approximation, a keystone of the models implemented, are evaluated using a molecular description of the silicon nano-crystals based on the method of linear combination of atomic orbitals. The second part of this work is more specifically centered on electronic transport under the Coulomb blockade regime. The description of the mechanisms of tunnel events is based on transfer Hamiltonian concept. Applied to the case of metallic and semiconductor Coulomb blockade devices (in particular to Metal-Insulator-Metal-Insulator-Metal and Metal-Insulator-Silicon Quantum Dot-Insulator-Metal structures), we have thus been able to implement a simulation software which only requires the knowledge of the fundamental physical parameters of the system. (author)