2D Semiconductors Directly Grown on Si with Room Temperature Mobility Exceeding 2000 cm ² V ⁻¹ s ⁻¹

Abstract Bi ₂ O ₂ Se 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 Bi ₂ O ₂ Se is limited to mica, or perovskite oxide substrates [SrTiO ₃ , LaAlO ₃ , (La, Sr)(Al, Ta)O ₃ ], incompatible with mainstream semiconductor processes, and the room temperature mobility is limited to ≈800 cm ² V ⁻¹ s ⁻¹ . Here, the controllable growth of Bi ₂ O ₂ Se nanoflakes on SiO ₂ /Si substrates is reported and with room temperature electron mobility higher than 2000 cm ² 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 Bi ₂ O ₂ Se. 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 Bi ₂ O ₂ Se sheds light to high‐performance electronic devices.