2 research outputs found
GaAsâFe<sub>3</sub>Si CoreâShell Nanowires: Nanobar Magnets
Semiconductorâferromagnet
GaAsâFe<sub>3</sub>Si coreâshell
nanowires were grown by molecular beam epitaxy and analyzed by scanning
and transmission electron microscopy, X-ray diffraction, MoÌssbauer
spectroscopy, and magnetic force microscopy. We obtained closed and
smooth Fe<sub>3</sub>Si shells with a crystalline structure that show
ferromagnetic properties with magnetizations along the nanowire axis
(perpendicular to the substrate). Such nanobar magnets are promising
candidates to enable the fabrication of new forward-looking devices
in the field of spintronics and magnetic recording
Polarity-Induced Selective Area Epitaxy of GaN Nanowires
We present a conceptually
novel approach to achieve selective area
epitaxy of GaN nanowires. The approach is based on the fact that these
nanostructures do not form in plasma-assisted molecular beam epitaxy
on structurally and chemically uniform cation-polar substrates. By <i>in situ</i> depositing and nitridating Si on a Ga-polar GaN
film, we locally reverse the polarity to induce the selective area
epitaxy of N-polar GaN nanowires. We show that the nanowire number
density can be controlled over several orders of magnitude by varying
the amount of predeposited Si. Using this growth approach, we demonstrate
the synthesis of single-crystalline and uncoalesced nanowires with
diameters as small as 20 nm. The achievement of nanowire number densities
low enough to prevent the shadowing of the nanowire sidewalls from
the impinging fluxes paves the way for the realization of homogeneous
core-shell heterostructures without the need of using <i>ex situ</i> prepatterned substrates