Bi2O2Se nanowires presenting high mobility and strong spin–orbit coupling

Abstract

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 cm2 V−1 s−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.