Computational investigations of the structure and properties of nanostructured materials

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In nanotechnology, miniaturization of devices towards the molecular scale can be efficiently achieved by designing fabrication components that assemble in predetermined ways and realize the desired complex or device. Nanoscale transistor arrays can be manufactured at the nanoscale using atomic layer deposition onto the gate conductor of highly conformal inorganic dielectric and semiconductor thin films. Working prototype transistors can be fabricated via self-assembly of organic dielectrics and semiconductors, with potential future application in the fabrication of smaller, more powerful computer chips, for charge storage and robotics applications. Block copolymers are designed to self-assemble into functional materials with designed properties. Bottom-up deposition and self-assembly processes are forecast as viable methods for fabrication of solar cells, sensors, and for in-vivo diagnosis and treatment. Despite significant recent advances, the current understanding of molecular and atomic deposition processes, and the chemical reactions taking place at the gas-surface interface, are still mainly empirical and fragmentary. Theoretical research can provide valuable insight into how a multitude of relevant factors interact and impact these processes. However, methodologies to account for local interactions when considering the system as a whole are still challenging to develop. By and large, current computational investigations either interpret experimental data, such as simulations based on empirical initial structures, neglect local interactions and treat the entire system in a coarse-grained fashion, or focus on materials where long range conformity makes local interactions unimportant. The nanostructured materials problems we are interested in are the result of a hierarchy of scales, and our research program aims, in the long run, to develop multi-scale approaches to investigate them. This involves a succession of steps: Developing an understanding of the local, molecular level behaviour, then using this understanding in the treatment of the macroscopic system as a whole, and finally providing feedback about the whole to the local calculations. In the short term, we will focus on three phenomena of significant practical importance: (a) Atomic layer deposition processes for the deposition of metals at oxide surfaces, with an emphasis on catalysis, substitution, and complex interactions. (b) Nanostructured surface formation, with an eye on packing, lattice mismatches, complex-structured substrate and competing minima on the potential energy surface. These phenomena have immediate applications for nanoscale devices, biosensors, and the fabrication of functional materials. (c) The optoelectronic properties of nanostructured materials, with an eye towards applications related to charge storage, photovoltaics and tunable dielectric and optical response.