AUTHOR=Weinert Tom , Hübner René , Facsko Stefan , Erb Denise J. 

TITLE=Bottom-up fabrication of FeSb2 nanowires on crystalline GaAs substrates with ion-induced pre-patterning

JOURNAL=Frontiers in Physics

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1149608

DOI=10.3389/fphy.2023.1149608

ISSN=2296-424X

ABSTRACT=Most industrial processes are generating waste heat that can be converted into electrical energy
with thermoelectric generators (TEGs). For efficient energy harvesting, it is necessary to significantly
improve the properties like Seebeck coefficient, electrical and thermal conductivity of the
thermoelectric materials in the TEGs. One promising approach are thermoelectric nanostructures
to reduce the thermal conductivity while maintaining constant electrical conductivity and Seebeck
coefficient. For that reason, this study investigated the possibility of preparing nanowires of
the thermoelectric material iron antimonide (FeSb2) on crystalline gallium arsenide GaAs(001)
substrates with ion-induced surface nanopatterning.
The GaAs(001) substrates were pre-patterned using 1 keV Ar+ ion irradiation. By using an
ion source with a broad, unfocused ion beam at normal incidence, the patterned area can be
scaled to nearly any size. The self-organized surface structure is formed by reverse epitaxy
and is characterized by almost perfectly parallel-aligned ripples at the nanometer scale. For
the fabrication of FeSb2 nanowires, iron and antimony were successively deposited on the prepatterned
GaAs substrates at grazing incidence and then annealed. They were characterized
using transmission electron microscopy (TEM), in particular high-resolution TEM imaging for
structure analysis and spectrum imaging analysis based on energy-dispersive X-ray spectroscopy
for element characterization.
With the presented fabrication method, FeSb2 nanowires were produced successfully on
GaAs(001) substrates with an ion-induced nanopatterned surface. The nanowires have a polycristalline
structure and a cross-sectional area which is scalable up to 22×22nm2. Due to the
highly ordered nanostructure of the GaAs substrates, the nanowires have a length of several
micrometer. These bottom-up nanofabrication based on ion-induced patterning can be a viable
alternative to top-down procedures regarding to efficiency and costs.