  Narrow bandgap InAs$_{1-x}$Sb$_x$ nanowires show broad prospects for
applications in wide spectrum infrared detectors, high-performance transistors
and quantum computation. Realizing such applications require the fine control
of composition and crystal structure of nanowires. However, to date, the
fabrication of large-composition-range pure-phase homogeneous
InAs$_{1-x}$Sb$_x$ nanowires remains a huge challenge. Here, we first report
the growth of large-composition-range stemless InAs$_{1-x}$Sb$_x$ nanowires (x
= 0-0.63) on Si (111) substrates by molecular-beam epitaxy. It is found that
pure-phase InAs$_{1-x}$Sb$_x$ nanowires can be successfully obtained by
controlling the antimony content x, nanowire diameter and nanowire growth
direction. Detailed EDS data show that the antimony is uniformly distributed
along the axial and radial directions of InAs$_{1-x}$Sb$_x$ nanowires and no
spontaneous core-shell nanostructures form in the nanowires. Based on
field-effect measurements, we confirm that InAs$_{1-x}$Sb$_x$ nanowires exhibit
good conductivity and their mobilities can be up to 4200 cm^2/V.s at 7 K. Our
work lays the foundation for the development of InAs$_{1-x}$Sb$_x$ nanowire
optoelectronic, electronic and quantum devices.
