Interface engineering is an effective strategy for enhancing thermoelectric performance by modulating carrier and phonon transport at interfaces. Atomic layer deposition (ALD), which enables uniform, conformal, and thickness-controlled coatings, is particularly well-suited for this purpose. In this study, p-type Bi0.35Sb1.6Te3 (BST) powders were coated with Al2O3 using thermal ALD and UV-assisted ALD (UV-ALD) at 85 °C. Scanning electron microscopy showed that neither process substantially altered the morphology of the BST powders. However, particle size analysis revealed that the UV-ALD sample exhibited a greater tendency toward partial agglomeration, which may be associated with the more pronounced OH-related band observed in the Fourier-transform infrared spectroscopy results. Cs-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping revealed continuous Al₂O₃-based coating layers approximately 2–3 nm thick on the BST particle surfaces, forming a core–shell structure. Fast Fourier transform analysis suggested that the coating layers were amorphous, and X-ray photoelectron spectroscopy indicated Al–O bond formation while the main chemical states of BST were preserved. These results demonstrate that both thermal ALD and UV-ALD can effectively deposit continuous amorphous Al₂O₃-based interfacial layers on BST powders, providing a structural basis for future studies of interface-engineered thermoelectric materials.

1. Introduction 
2. Experimental Section 
3. Results and Discussion 
4. Conclusion 
Funding
Conflict of Interest 
Data Availability Statement 
Author Information and Contribution 
Acknowledgments
References

• Yeongtae Choi(MAJE TECHNOLOGY Co. Ltd., Suwon 16426, Republic of Korea)
• Jin Kyeong Shin(Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• Byung Joon Choi(Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea) Corresponding author