Characteristics like air-stability and high carrier mobility make non-van-der-Waals layered Bi2O2Se a good prospect for planar integrated nanosystems. However, experimental investigation about its analogue Bi2O2Te is rather rare due to difficulty in synthesis. Herein, a low-pressure CVD process is proposed that is adjusted to the rigorous growth condition required, with large-scale Bi2O2Te ultrathin film obtained. Magneto-transport behavior reveals a very large anisotropic nonsaturating low-temperature magnetoresistance (∼1133% under 9 T magnetic field). Despite the contradiction between high conductivity and ferroelectricity in principle (mobile electrons screen electrostatic forces between ions), the high-conductive Bi2O2Te film here is revealed experimentally as another intrinsic ferroelectric with the polarization switchable by external electric field (predicted in Nano Lett. 2017, 17, 6309). These results prove that Bi2O2Te possesses a very narrow bandgap (∼0.15 eV), high conductivity, large magnetoresistance, and room-temperature ferroelectricity, displaying great potential as a high-performance nanoelectronic two-dimensional semiconductor and, in advanced functional devices, working in the mid-infrared region.
Keywords: Bi2O2Te; chemical vapor deposition; ferroelectricity; large magnetoresistance; two-dimensional materials.