Bi<sub>2</sub>O<sub>2</sub>Se photoconductive detector with low power consumption and high sensitivity

Abstract

With the advent of graphene, atomically thin two-dimensional materials receive great attention in both science and technology. However, the characterization of zero-band gap of graphene hinders its applications in semiconductor logic and memory devices. To make up for the imperfection of graphene, one has made efforts to search for other two-dimensional layered materials. The Bi<sub>2</sub>O<sub>2</sub>Se is an emerging material with very high electron mobility, modest bandgap, and excellent thermal and chemical stability. In this work, high-quality Bi<sub>2</sub>O<sub>2</sub>Se thin films are synthesized through chemical vapor deposition. The effect of temperature on the morphology and size distribution of Bi<sub>2</sub>O<sub>2</sub>Se thin film are discussed in detail experimentally. Under an optimized experimental condition, the Bi<sub>2</sub>O<sub>2</sub>Se thin films with a lateral size of 100 μm are achieved. Interestingly, Bi<sub>2</sub>O<sub>2</sub>Se nanowires are obtained at a lower growth temperature (620–640 ℃). The photoelectric performances of Bi<sub>2</sub>O<sub>2</sub>Se on mica and silicon oxide substrate are examined based on a photoconductive mode. At a small bias of 0.5 V, the responsivity and specific detectivity of the rectangular Bi<sub>2</sub>O<sub>2</sub>Se thin film on the mica substrate reach 45800 A/W and 2.65 × 10<sup>12</sup> Jones, respectively, and the corresponding photoelectric gain is greater than 10<sup>5</sup>. The photoelectric performance of our device is comparable to the best results achieved by other research groups, which may be related to the higher quality and appropriate absorption thickness. The Bi<sub>2</sub>O<sub>2</sub>Se nanowire and Bi<sub>2</sub>O<sub>2</sub>Se thin film transferred to Si/SiO<sub>2</sub> by a polystyrene-assisted method also exhibit a good photoresponse under the illumination of a 532 nm laser with a high optical power density (127.4 mW/cm<sup>2</sup>). The experimental results demonstrate that the Bi<sub>2</sub>O<sub>2</sub>Se has great potential applications in the optoelectronic devices with low power consumption and high sensitivity.