High-Performance Near-Infrared Photodetector Based on Ultrathin Bi2O2Se Nanosheets

As an emerging 2D layered material, Bi2O2Se has shown great potential for applications in thermoelectric and electronics, due to its high carrier mobility, near-ideal subthreshold swing, and high air-stability. Although Bi2O2Se has a suitable band gap for infrared (IR) applications, its photoresponse properties have not been investigated. Here, high-quality ultrathin Bi2O2Se sheets are synthesized via a low-pressure chemical vapor deposition method. The thickness of 90% Bi2O2Se sheets is below 10 nm and lateral sizes mainly distribute in the range of 7-11 mu m. In addition, it is found that triangular sheets largely lack O content, even only 0.2 for Bi2O0.2Se. The near-IR photodetection performance of Bi2O2Se nanosheets is systematically studied by variable temperature measurements. The response time, responsivity, and detectivity can approach up to 2.8 ms, 6.5 A W-1, and 8.3 x 10(11) Jones, respectively. Additionally, the critical performance parameters, including responsivity, rising time, and decay time, remain at almost the same level when the temperature is changed from 80 to 300 K. These phenomena are likely due to the fact that as-grown ultrathin Bi2O2Se sheets have no surface trap states and shallow defect energy levels. The findings indicate ultrathin Bi2O2Se sheets have great potentials for future applications in ultrafast, flexible near-IR optoelectronic devices.