| dc.description.abstract | One-dimensional semiconductor structures have attracted a large research interest,
mainly for the purpose of novel or improved opto-electronic properties and
applications. In this work, semiconductor nanowires grown using the vapor-liquidsolid
method are characterized using electron microscopy based techniques, in order
to understand and improve nanowire synthesis and nanowire-based devices.
Methods and tools have also been developed to improve and expedite such characterizations.
One area of focus in the work has been on nanowire interfaces, especially the
interface between GaAs nanowires and graphene substrates. Here, the symmetry
and lattice mismatch have been considered, and the consequences this has on
nanowire epitaxy on graphene. In addition, the study has focused on in situ characterization
of nanowires and their interfaces, both in focused ion beam systems
and in electron microscopes, with the goal of correlating the functional properties
with the observed composition and structural features. Here, both the electrical
properties of the nanowires and the dynamic behavior under heat-treatment have
been studied.
The main findings of the work include the proof of GaAs nanowire growth directly
on few-layer graphene, as well as the quantitative description of the solid
state replacement of GaAs nanowires by Au during heat-treatment. Additionally,
techniques to characterize the mechanical and electrical characteristics of the
nanowire–substrate interface have been further developed. Large contributions to
collaborative, open source analysis software have also been made. These developed
tools were essential for obtaining more informative results from the experimental
data. | nb_NO |
