  Self-assembled, semimetallic ErSb single crystal nanostructures, grown by
molecular beam epitaxy, are embedded within a semiconductor GaSb matrix.
Formation, evolution and orientation of a variety of nanostructures, including
spherical nanoparticles, elongated nanorods, octagonal shaped nanowires
oriented along the surface normal and nanowires oriented in the growth plane,
are controlled simply by the Er fraction. The plasmonic properties of the
semimetal/semiconductor composites are characterized and quantified by three
polarization-resolved spectroscopy techniques, spanning more than three orders
of magnitude in frequency from 100 GHz up to 300 THz. The effect of the size,
shape and orientation of the nanostructures is characterized by
polarization-sensitive response and modeled by a Maxwell-Garnett effective
medium theory.

Materials Science