An attractive feature of ALD is that it is able to deposit metals, metal oxides and other compounds at lower temperatures than other vapor-based deposition processes. Our group specifically explores the lower-end temperature range of ALD reactions and materials to discover unique process mechanisms, as well as new application areas that can result from very low temperature ALD. As one broad area of low-temperature ALD, we are particularly interested in ALD materials and processes on high surface area fibers and textiles, for applications in advanced personal protection, flexible electronics, chemical detection and sensing, and other applications.
The figure at left shows transmission electron microscopy (TEM) images of nanofiber materials that have been coated with metal oxide by Atomic Layer Deposition in our laboratory. Because the ALD process proceeds through a nano-scale sequence of self-limiting surface reactions, the resulting deposition covers the fibers uniformly and conformally. In some cases, the ALD reactants can diffuse into the near-surface layer of the polymer, resulting in a gradation of the coating near the fiber surface. Our work sheds light on understanding the nature of how particular ALD processes proceed on different polymer surfaces.