Mass analysis of growth of AL ₂O ₃ thin films from low-temperature atomic layer deposition on woven cotton

Atomic layer deposition (ALD) at 100°C provides a conformal coating on woven cotton with a tortuous and complex surfaces. The woven structures are completely preserved and replicated with thin coating of Al ₂O ₃, even after removing the cotton templates. The replicated woven structures enable direct mass analysis of the cotton coating. Quantitative analysis reveals that the self-limiting reaction of ALD is ensured, even on tortuous cotton surfaces, except for early growth cycles. This unique feature of ALD assures conformal coating onto three-dimensional (3D) networks of cotton. The results demonstrate the possibility of a non-local methodology for evaluating the thickness of a coating on 3D objects at various stages of growth.