Impact of precursor concentration on topology, wettability and electrical properties of Zn2SnO4 films obtained by spray-pyrolysis

Abstract

In this study, Zn₂SnO₄ thin films were synthesized using the spray-pyrolysis technique with varying precursor concentrations (0.05 M, 0.15 M, 0.3 M) to investigate their influence on film topology, wettability, and electrical properties, aiming to explore their potential applications in photodetectors and microfluidics. The grown oxide films were analyzed by atomic force microscopy (AFM) to study their roughness. The films were found to be generally smooth, but the surface roughness increased from 6 nm to 12 nm (RMS) as the precursor concentration increased from 0.05 M to 0.30 M, with maximum peak height (Sp) reaching up to 42 nm. Contact angle measurements revealed that the degree of hydrophobicity increased from 119° to 124° with increasing precursor concentrations. Electrical characterization by current-voltage measurements showed that the photocurrent to dark current ratio peaked at 34 for the precursor concentration of 0.15 M, compared to 17 and 22 for 0.05 M and 0.30 M, respectively, under a bias of 3 V and an excitation density of 100 mW/cm2. These results reveal a strong correlation between precursor concentration and film morphology, wettability, and conductivity. Notably, the study provides a systematic analysis of how precursor concentration variations enable fine-tuning of Zn₂SnO₄ film properties, highlighting the versatility of the spray pyrolysis method and its potential for scalable production. This work contributes to scientific innovation by demonstrating how process parameters can be designed to optimize functional thin films for applications in optoelectronic and sensing devices.