Abstract

The one-dimensional nanoribbons made from phosphorene are novel structures with great applicability potential in material science. The significant carrier mobility combined with intrinsic semiconductor properties makes them ideal for application in electronics, and they are excellent candidates for sensing material. The lack of a well–established multiscale modelling strategy for phosphorene nano optoelectronic devices is one of the issues slowing down research on its applications. This thesis is focused on the preparation of the hybrid workflow for complex modelling of the phosphorene nanoribbons and use it for studying the potential of applying phosphorene nanostructures as a mechanical nanooscillator. In the proposed design, the oscillating behaviour of phosphorene device can be traced by the changes in the Raman bands of this structures. To efficiently predict the magnitude of such change, the multi-stage, hybrid calculation workflow was constructed. The ab initio modelling was utilised to study the mechanical elasticity of the phosphorene nanoribbons with different widths and doping levels. The effect of surface oxidation and interaction with air humidity was also studied using ab initio molecular dynamics. The Raman bands shifts dependence on the strain, and the level of surface oxidation was also calculated using the ab initio method in frozen phonon approximation. The properties calculated for atomic models of nanoribbons were used to model the dynamical behaviour of the phosphorene nanoribbons. The phosphorene nanoribbons aspect ratios are very high, and because of that, the atomic models used in ab initio modelling were a few orders of magnitude smaller than the size of the ribbons. To extrapolate the properties of these models into microscopic structures, the finite element method (FEM) was implemented, and the atomic models of the ribbons were designed to be infinitesimal elements of the structures. Because of this synergic application of both quantum and classical modelling, this approach is called hybrid. The results achieved for the structures using the hybrid approach were compared with the force field calculations, presenting consistency between methods and significantly lower computational cost of hybrid modelling in comparison to whole structure force field modelling.

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