First principles investigations of quantum transport for nano-electronic applications

Abstract

The ability to control the transport of electrons across nanometer-sized junctions made from molecules and nanostructures has revolutionalized the field of electronics by introducing new electronic circuit device components made from single atoms, molecules and nanostructures. This emerging field, known as nanoelectronics, has witnessed enormous amount of innovation in the fundamental as well as the technological aspects of the transport problem, greatly advancing our knowledge of quantum effects in transport at the nano-level, as well as broadened that application of electronics to areas that have been inaccessible with the traditional silicon technologies. Numerous reports have demonstrated the exceptional transport capabilities of molecules and nanostructures, showing that we are about to witness the violation of Moore's law. Nowadays, the applications of nanoelectronics are rapidly expanding both in terms of academic research as well as in industry. Examples of promising applications include the development molecular-scale electronic circuits, biosensors and futuristic molecule-based computing. Given that the technologies in molecular and nanoelectronics operate at the molecular and atomic scale, a necessary ingredient of the skills required for developing these technologies is the understanding of the quantum nature of transport phenomena. In the present Thesis we apply proven ab initio quantum transport methods in the time-independent and time-dependent formalisms in order to simulate transport phenomena in various systems and physical conditions. We have examined rectification, spin-filtering, switching, negative differential resistance and charge migration in various nanostructures including a novel diamondoid-cumulene hybrid structure. These investigations provided predictions of novel quantum transport behavior in various nanostructures that would drive future research towards their experimental realization.