Ultraviolet to near infrared wavelength independent SnS-graphene hybrid thin film photodetector from nanocolloids

It is crucial and imperative to produce wavelength-independent photodetectors as most of the reported devices are limited by their operating wavelength region. We report graphene incorporated tin sulfide (SnS) hybrid thin films as photodetectors operational in the ultrabroadband range of wavelength using their nanocolloids. SnS nanocolloids obtained by Pulsed Laser Irradiation in Liquid (PLIL) performed by irradiating SnS powder using 532 nm laser output (Nd:YAG) is the first report on SnS by PLIL. Into this nanocolloid, graphene was ultra-sonically dispersed. SnS-graphene hybrid films were deposited by spin-coating followed by annealing in vacuum. The morphological study of the films revealed graphene layers hybridized with spherical SnS nanoparticles. Raman analysis, X-ray diffraction and X-ray photoelectron spectroscopy results confirmed the phase, structure and chemical composition. A bandgap of 2.1-2.0 eV was obtained for the annealed SnS films and graphene addition helped in extending the absorption range over the entire UV-Vis-NIR reducing the bandgap values to 1.8-1.5 eV. The films showed high photoresponse independent of the different wavelengths of illumination. The hybrid photodetector exhibits a specific detectivity of 107 Jones and a responsivity of 10-5 AW-1. The SnS-graphene hybrid photodetectors, being wavelength-independent, are a promising candidate for optoelectronic applications.