Publications by authors named "A Biermanns"
In III-V nanowires the energetic barriers for nucleation in the zinc blende or wurtzite arrangement are typically of a similar order of magnitude. As a result, both arrangements can occur in a single wire. Here, we investigate the evolution of this polytypism in self-catalyzed GaAs nanowires on Si(111) grown by molecular beam epitaxy with time-resolved in situ x-ray diffraction.
View Article and Find Full Text PDFWe present the results of the study of the correlation between the electrical and structural properties of individual GaAs nanowires measured in their as-grown geometry. The resistance and the effective charge carrier mobility were extracted for several nanowires, and subsequently, the same nano-objects were investigated using X-ray nanodiffraction. This revealed a number of perfectly stacked zincblende and twinned zincblende units separated by axial interfaces.
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- InAs nanowires grown without catalysts along the [111] direction face difficulties controlling their crystal phase due to polytypism between wurtzite and zincblende structures.
- The study uses time-resolved X-ray scattering to examine how growth conditions affect the nanowires' structure, noting that the presence of liquid indium supports the formation of predominantly wurtzite-phase nanowires.
- High arsenic-rich conditions limit liquid indium formation, leading to structural defects in the wurtzite phase, indicating that consistent indium presence during growth is necessary for achieving high phase purity in these nanowires.
InAs segments were grown on top of GaAs islands, initially created by droplet epitaxy on silicon substrate. We systematically explored the growth-parameter space for the deposition of InAs, identifying the conditions for the selective growth on GaAs and for purely axial growth. The axial InAs segments were formed with their sidewalls rotated by 30° compared to the GaAs base islands underneath.
View Article and Find Full Text PDFWe report the impact of deposition parameters on the structure of HfO(2) covering InAs nanowires (NWs) being potential candidates for future field-effect transistors (FETs). Molecular beam epitaxial-grown Au-free InAs NWs were covered with HfO(2) deposited by atomic-layer deposition. The impact of the film thickness as well as the deposition temperature on the occurrence and amount of crystalline HfO(2) regions was investigated by high-resolution transmission electron microscopy (TEM) and x-ray diffraction.
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