Photosensitivity properties of Eu-doped SnS 2 thin films deposited by cost-effective nebulizer spray pyrolysis technique

The current research explores the outcome of europium doping on the structure, morphology, electrical conductivity and optoelectronic characteristics of SnS 2 thin films deposited on glass substrates by nebulizer spray technique. X-ray diffraction analysis substantiates the presence of hexagonal structure in both pure and Eu-doped SnS 2 thin films with the highly preferred orientation diffracted from the plane (002). It shows the intensity of the predominant peak is highest for 2% Eu-doped SnS 2 thin film. From the XRD data, the crystallite size was found to be highest for 2% SnS 2 :Eu, and same sample showed a less dislocation density of 0.97 × 10 15 lines/m 2 and microstrain of 0.081 × 10 –3 /lines 2 m 4 . The crystallite size first increases with increasing doping concentration of Eu (0–2%), then decreases for higher concentrations. The SEM and AFM micro images reveal the agglomeration of grains at higher Eu concentration. The compositional analysis through EDAX studies supports the presence of Eu, Sn and S. The SnS 2 optical band gap value is found to vary from 2.70 to 2.91 eV as the Eu doping is increased from 2 to 6%. All the SnS 2 thin film samples manifest a n-type conductivity as authenticated from Hall studies and a low resistivity of 4.34 × 10 −1 cm with an elevated carrier concentration of 5.43 × 10 17 cm −3 , respectively, was observed for SnS 2 :Eu (2 wt%). The same sample established a higher responsivity (41.64 × 10 −3 AW −1 ), competent external quantum efficiency (97.24%), and a better detectivity (40.88 × 10 8 Jones). Hence, the 2% Eu-doped SnS 2 film is recognized to be best suited for the fabrication of high-speed optoelectronic devices. This paper also discusses a putative mechanism for photo-detector performance under air and UV radiation.