Nanoscale surface morphology of Cu2CdSnS4 quaternary alloy nanostructures synthesized by spin coating technique and deposited with ultrasonic treatment

• AFM, PSD, fractal, and motif analysis assessed surface morphology changes. • Fractal dimensions increased from 2.32 (RT) to 2.87 (500 °C), indicating higher complexity. • Frequency spectrum analysis confirmed isotropic surface characteristics. • Magnitude increased from -91.2 dBc (RT) to -58.5 dBc (500 °C), showing increased roughness. • Peak and pit motifs decreased in size and height at 500 °C. The surface morphology of Cu 2 CdSnS 4 quaternary alloy nanostructures synthesized using the spin coating technique and treated with ultrasonic assistance at various temperatures (RT, 300 °C, 400 °C, and 500 °C) was examined using atomic force microscopy (AFM). The study aimed to understand the influence of temperature on surface features, texture, and periodicity. The analysis included frequency spectrum, fractal dimensions, motif analysis, and various surface statistical parameters. The frequency spectrum showed consistent wavelength and angle values across all temperatures, signifying isotropy. However, magnitude values varied, reflecting the prominence of surface features, from −91.2 dBc at RT to −58.5 dBc at 500 °C. Fractal analysis revealed that fractal dimensions increased from 2.32 at RT to 2.87 at 500 °C, indicating enhanced surface complexity with higher temperatures. Motif analysis demonstrated that the number of motifs increased with temperature, with peak and pit sizes growing at 300 °C, then reducing in height and area at 500 °C. Additionally, the skewness and kurtosis values transitioned from sharp peaks at RT to a more balanced surface at 300 °C, before increasing again at 500 °C, aligning with surface feature changes. Surface height parameters such as Sq and Sa peaked at 300 °C and decreased significantly at 500 °C. These changes correlate with the material’s evolving surface structure, which becomes more refined and isotropic with increasing temperature, making it suitable for advanced material applications.