Simulating the effect of structural imperfections on nanowire transport properties using kwant

Sammanfattning: Conductance was calculated for trapezoidal nanowires with different forms and strengths of imperfection using kwant, a quantum transport software package that uses a tight-binding model. In this thesis it is found that increasing magnitudes of different imperfections such as surface charge and roughness roughen conductance steps, introduce resonances, and lower conductance overall with different character of these effects for different types of imperfections. Quantitative qualification of the effect on conductance is calculated in the form of exponential fits for Urbach tails, showing a more gradual increase in conductance as the strength of imperfections increases. These results show how different imperfections can affect transport properties in nanowires, and provide insight which can help provide a more concrete theoretical understanding of the transport-imperfection relationship as well as aid the design and characterisation of next-generation nanowire devices.