Scalable fabrication of Bi_2O_2Se polycrystalline thin film for near-infrared optoelectronic devices applications

We present a controlled, stepwise formation of layered semiconductor Bi₂O₂Se thin films prepared via the vapour process by annealing topological insulator Bi₂Se₃ thin films in low oxygen atmosphere for different reactions. Photodetectors based on Bi₂O₂Se thin film show a responsivity of 1.7×10⁴ A/W at a wavelength of 980 nm. Field-effect transistors based on Bi₂O₂Se thin film exhibit n-type behavior and present a high electron mobility of 17 cm²/V·s. In addition, the electrical properties of the devices after 4 months keeping in the air shows little change, implying outstanding air-stability of our Bi₂O₂Se thin films. From the obtained results, it is evident that low oxygen annealing is a surprisingly effective method to fabricate Bi₂O₂Se thin films for integrated optoelectronic applications.