  Systematic electrical transport characterizations were performed on
high-quality Bi2O2Se nanowires to illustrate its great transport properties and
further application potentials in spintronics. Bi2O2Se nanowires synthesized by
chemical vapor deposition method presented a high field-effect mobility up to
1.34*104 cm2V-1s-1, and exhibited ballistic transport in the low back-gate
voltage (Vg) regime where conductance plateaus were observed. When further
increasing the electron density by increasing Vg, we entered the phase coherent
regime and weak antilocalization (WAL) was observed. The spin relaxation length
extracted from the WAL was found to be gate tunable, ranging from ~100 nm to
~250 nm and reaching a stronger spin-obit coupling (SOC) than the
two-dimensional counterpart (flakes). We attribute the strong SOC and the gate
tunability to the presence of a surface accumulation layer which induces a
strong inversion asymmetry on the surface. Such scenario was supported by the
observation of two Shubnikov-de Haas oscillation frequencies that correspond to
two types of carriers, one on the surface, and the other in the bulk. The
high-quality Bi2O2Se nanowires with a high mobility and a strong SOC can act as
a very prospective material in future spintronics.
