Single Bi2S3/Bi2S3-xOx nanowire photodetector with broadband response from ultraviolet to near-infrared range

Constructing heterojunction in single nanowire (NW) can improve the band alignments of heterogeneous interface to promote the optoelectronic performance of materials. In this paper, Bi2S3/Bi2S3-xOx heterojunction NWs are in situ constructed by surface oxidation technique to fill the vacancies of sulfur with oxygen atoms into Bi2S3 NWs. According to the first principle calculation, Bi2S3-xOx shell possesses a narrower band gap of 1.32 eV than that of Bi2S3 core, which aids NW further to enlarge the response range of near infrared spectrum. Moreover, n-type Bi2S3 converts to p-type Bi2S3-xOx owing to the incorporation of oxygen atoms in the surface of the NWs based on the calculated electronic structures. The band alignment of Bi2S3/Bi2S3-xOx heterojunction contributes to transform the carriers between the interface of Bi2S3 and Bi2S3-xOx. As a result, the single Bi2S3 NW based photodetector presents a broadband response from ultraviolet light of 325 to near-infrared light of 1064 nm. Moreover, the detectivity of photodetector is up to 1011 Jones for the visible light of 405, 442 and 642 nm. This investigation demonstrates an efficient broadband photodetector based on Bi2S3/Bi2S3-xOx NWs, in which provides an effective route to develop the high performance of optoelectronic devices for the other NWs.