Morphological and Thickness Characterization of SnO₂ Thin Films Deposited via Ultrasonic Spray Coating

In this study, tin oxide (SnO₂) thin films were deposited using the UltraSprayer Starter ultrasonic spray coating system. The influence of process parameters on film thickness uniformity, surface morphology, and nanoscale topography was systematically investigated.

Cross-sectional SEM analysis (a–c):
The films exhibit a continuous and uniform thickness distribution across the substrate. The absence of delamination or discontinuities indicates controlled droplet deposition and solvent evaporation dynamics.

Surface SEM analysis (d–f):
A densely packed nanostructured morphology is observed, with well-distributed grain formations. These results highlight the critical role of droplet size control and substrate temperature management in nucleation and grain growth mechanisms.

AFM characterization (g–i):
Topographical analysis reveals a consistent and reproducible surface roughness profile with nanoscale features, confirming stable and well-controlled process conditions.

Although nozzle motion was not applied in this study, a high degree of uniformity was achieved. In systems where nozzle motion is actively integrated, such as UltraSprayer Essential and Pro, further improvements in surface uniformity are expected.

Key Findings:
• High thickness uniformity
• Controlled nanostructured surface morphology
• Reproducible surface roughness
• Strong correlation between process parameters and film quality

Process Insight:
The study emphasizes the importance of:
– Controlled droplet generation via ultrasonic atomization
– Substrate temperature homogeneity
– Optimized drying and crystallization conditions
These parameters directly influence the functional performance of optoelectronic thin films, particularly in sensor, optoelectronic, and energy-related applications.

Ultrasonic spray coating using UltraSprayer Starter platform enables the fabrication of high-quality, homogeneous, and reproducible SnO₂ thin films, making it a reliable and scalable approach for advanced material applications.