2D Semiconductors Directly Grown on Si with Room Temperature Mobility Exceeding 2000 cm² V^-1 s^-1

Bi₂O₂Se has recently attracted immense interest in nanoelectronics and optoelectronics for its superior mobility, ferroelectric order, tunable bandgap, and exceptional air stability. However, until now, the direct growth of Bi₂O₂Se is limited to mica, or perovskite oxide substrates [SrTiO₃, LaAlO₃, (La, Sr)(Al, Ta)O₃], incompatible with mainstream semiconductor processes, and the room temperature mobility is limited to ≈800 cm² V^-1 s^-1. Here, the controllable growth of Bi₂O₂Se nanoflakes on SiO₂/Si substrates is reported and with room temperature electron mobility higher than 2000 cm² V^-1 s^-1, exceeding all previous reports. The unpreceded in-plane electron mobility is found to strongly correlate with the out-of-plane ferroelectric order, which is stabilized by the expanded c-lattice in oxygen-deficient Bi₂O₂Se. The stabilized ferroelectric phase is confirmed by piezoresponse force microscopy (PFM) and anisotropic transport property measurements, which generally possess a high dielectric constant, thus reducing the impurity scattering. The silicon-compatible ultrahigh mobility Bi₂O₂Se sheds light to high-performance electronic devices.