Growth and Characterization of InGaAs based Nanowire-Heterostructures

In this thesis we investigate III-V semiconductor nanowires integrated on silicon. Focusing on InGaAs-based heterostructures, we use molecular beam epitaxy to obtain high purity material without the use of foreign metal catalysts such as gold. Instead of catalyst-assisted growth we use selective-area growth using prepatterned SiO2/Si(111) substrates prepared by improved nanoimprint lithography, resulting in highly periodic large scale arrays (1×1 cm²) of vertically aligned nanowires with hexagonal cross-section.
Studying the influence of the main growth parameter substrate temperature, arsenic- and III-material flux we systematically optimize yield and aspect ratio of InAs nanowires for different spacings. Capitalizing on the superior morphological homogeneity of arrays with more than 90% yield, we study their use as efficient surface emitters in the Terahertz regime and find excellent performance, clearly outperforming state-of the art bulk material, when taking the surface coverage into account. Furthermore, we explore nanowires with strongly reduced diameter, where adapted growth conditions result in dimensions as small as 20 nm, well within a quantum confined regime.