  Semiconducting nanowires offer many opportunities for electronic and
optoelectronic device applications due to their special geometries and unique
physical properties. However, it has been challenging to synthesize
semiconducting nanowires directly on SiO2/Si substrate due to lattice mismatch.
Here, we developed a catalysis-free approach to achieve direct synthesis of
long and straight InSe nanowires on SiO2/Si substrate through
edge-homoepitaxial growth. We further achieved parallel InSe nanowires on
SiO2/Si substrate through controlling growth conditions. We attributed the
underlying growth mechanism to selenium self-driven vapor-liquid-solid process,
which is distinct from conventional metal-catalytic vapor-liquid-solid method
widely used for growing Si and III-V nanowires. Furthermore, we demonstrated
that the as-grown InSe nanowire-based visible light photodetector
simultaneously possesses an extraordinary photoresponsivity of 271 A/W,
ultrahigh detectivity of 1.57*10^14 Jones and a fast response speed of
microsecond scale. The excellent performance of the photodetector indicates
that as-grown InSe nanowires are promising in future optoelectronic
applications. More importantly, the proposed edge-homoepitaxial approach may
open up a novel avenue for direct synthesis of semiconducting nanowire arrays
on SiO2/Si substrate.
