A new approach for broadband photosensing based on Ag2Se/Si heterojunction tuned by Pyro-phototronic effect

With its high carrier mobility and low effective mass characteristics, silver selenide (Ag 2 Se) emerges as an attractive candidate for use in optoelectronic devices . However, the relatively low responsivity , slow response speed, and need for a large external bias largely limit their practical applications. In this manuscript, a newly photodetector (PD) is fabricated based on the n-Ag 2 Se/p-Si heterojunction . It is observed that this PD exhibits a broadband response range of 405–1064 nm at zero bias, and the best responsivity ( R ) and detectivity ( D ) are obtained to be 3.04 mA/W and 1.67 × 10 10 Jones at 1064 nm, respectively, demonstrating its great potential in high-performance self-powered near-infrared (NIR) PD. More importantly, the light-induced pyroelectric effect, which can be employed to modulate the photoelectric processes and improve the photoresponse, is found in the Ag 2 Se film due to the imperfect orthorhombic structure. When the Pyro-phototronic effect is introduced in the heterojunction , the R and D of the PD are significantly enhanced to 43.32 mA/W and 1.75 × 10 11 Jones with an argument of 1425 % , respectively. An ultrafast response time of 64/62 μs is simultaneously achieved under the illumination of a 400 Hz-pulsed laser, the performances of which are much better than those of previously reported Ag 2 Se-based heterostructure PDs. Besides, the response range is broadened beyond the bandgap of the heterojunction to a near-infrared region of 1550 nm. This study provides a novel pyroelectric material-based self-powered broadband PD and also gives a great promise for designing high-performance infrared ultrafast PD based on the Pyro-phototronic effect. A newly photodetector (PD) is fabricated based on the n-Ag 2 Se/p-Si heterojunction. This PD exhibits a broadband response range of 405–1064 nm at zero bias, and the best responsivity ( R ) and detectivity ( D ) are obtained to be 3.04 mA/W and 1.67 × 10 10 Jones at 1064 nm, respectively. Moreover, owing to the Pyro-phototronic effect of the Ag 2 Se layer, the R and D of the PD are significantly enhanced to 43.32 mA/W and 1.75 × 10 11 Jones with an argument of 1425 % , respectively, and an ultrafast response time of 64/62 μs is simultaneously achieved. Besides, the response range is broadened beyond the bandgap of the heterojunction to a near infrared region of 1550 nm. • A newly narrow-band pyroelectric material of Ag 2 Se is obtained and prepared as a self-powered photodetector. • Photoresponse are greatly improved by introducing Pyro-electronic effect with an increment reaching up to 3122 %. • An ultrafast response time of 64/62 μs is achieved, and the response range is broadened to 1550 nm.