Dynamics of Shuttle Devices

Foreword This thesis is submitted in candidacy for the Ph.D. degree within the Physics Program at the Technical University of Denmark. The thesis describes part of the work that I have carried out under supervision of Antti-Pekka Jauho from the Department of Micro and Nanotechnology. I'm grateful to my supervisor for the very stimulating atmosphere that he has been able to create and maintain within his group and also for his gentle but firm guidance. I want to thank all the members of the Theoretical Nanotechnology Group at the MIC Department and in particular Dr. Tomáš Novotn´y and Christian Flindt for the close and intense collaboration that has generated a large part of the results presented in this thesis. I would like to thank Prof. Timo Eirola for having introduced me to the subject of the iterative numerical methods and for his precious help in the solution of some of the numerical problems I encounter in my research. I want also to thank Dr. Tobias Brandes and Neill Lambert for the nice physics discussions I could have with them during the period I spent collaborating with them in Manchester. I want to thank Christian Flindt also for the enthusiasm and the very positive attitude that he has been always able to spread within the " Shuttle Group ". He has also been an indefatigable reader of the proofs and deserves many thanks for that. Finally I also want to thank my family for their far but constant support and all the Italian friends in Copenhagen for being very patient and encouraging me during the writing period. Preface Much interest has been drawn in recent years to the concept and realization of Nanoelectromechanical systems (NEMS). NEMS are nanoscale devices that combine mechanical and electrical dynamics in a strong interplay. The shuttle devices are a particular kind of Nanoelectromechanical systems. The characteristic component that gives the name to these devices is an oscillating quantum dot of nanometer size that transfers electrons one-by-one between a source and a drain lead. The device represents the nano-scale analog of an electromechanical bell in which a metallic ball placed between the plates of a capacitor starts to oscillate when a high voltage is applied to the plates. This thesis contains the description and analysis of the dynamics of two realizations of quantum shuttle devices. We describe the dynamics using the Generalized Master Equation approach: a well-suited …