Tailoring the physical properties of ultrasonically spray pyrolyzed SnS thin films with silver doping

In this study, the effects of silver (Ag) doping on the structural, morphological, optical, and electrical properties of tin monosulfide (SnS) thin films were investigated. The films, undoped and doped with 3%, 6%, and 9% Ag, were deposited using the ultrasonic spray pyrolysis (USP) technique at a substrate temperature of 350 degrees C. X-ray diffraction (XRD) analysis confirmed a pi-SnS (cubic) structure with (400) preferred orientation for undoped and <= 6% Ag-doped films, while 9% doping induced amorphization due to severe lattice distortions. Morphological analyses revealed smooth, void-free surfaces, with average roughness increasing from 5.8 nm (undoped) to 19.6 nm (9% doping). Optical measurements showed that the band gap widened from 1.84 eV (undoped) to 2.47 eV (9% Ag-doped), and Urbach energy increased from 190 meV to 600 meV. Hall effect measurements confirmed p-type conductivity for all films. Resistivity ranged from 4.34 x 10(5) Omega cm to 9.48 x 10(5) Omega cm, carrier concentration varied between 2.7 x 10(12) cm(-3) and 5.6 x 10(12) cm(-3), while mobility decreased from 3.3 x 10(1) cm(2)/Vs to 2.0 x 10(1) cm(2)/Vs with increasing Ag doping. These findings demonstrate that Ag doping significantly influences the structural and optoelectronic behavior of SnS thin films, making them promising candidates for thin-film solar cells and optoelectronic applications.