Synthesis and characterization of group II-Vi semiconductor nanowires

Semiconductor nanowires are an emerging class of nanostructures that represent attractive building blocks for nanoscale electronic and photonic devices. To the present, nanowires are synthesized on a small scale by experimentally demanding gas phase deposition techniques. This thesis describes a simple and cost-efficient solution-based synthesis towards high-quality nanowires of Group II-VI compound semiconductors. The effects of various reaction parameters and of doping on the wires' structural, electrical and magnetic properties are investigated. The first part of this thesis is dedicated to a novel variant of the solvothermal synthesis of CdS nanowires employing a single-source precursor. The wires are of single-crystalline quality and can be indexed to wurtzite-type bulk CdS with the preferential growth direction along the axis. As-grown nanowires have a smooth surface, are up to 40 µm long and exhibit aspect ratios up to 1000. The wires' aspect ratio can be increased by choosing a low precursor concentration. Time-dependent experiments reveal the wires to axially grow at a rate of ≈1µm/h while lateral growth only occurs during the initial reaction phase. As shown by photoluminescence spectroscopy the surface defect density can be significantly lowered by raising the reaction temperature from 180 to 200 °C. Electrically contacted CdS nanowires are highly resistive in the dark, but become more conductive by 4 orders of magnitude upon illumination above the bandgap energy (λ