AVS 51st International Symposium
    Thin Films Tuesday Sessions
       Session TF2-TuM

Paper TF2-TuM9
Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials

Tuesday, November 16, 2004, 11:00 am, Room 303C

Session: ALD and Applications
Presenter: J.W. Elam, Argonne National Laboratory
Authors: J.W. Elam, Argonne National Laboratory
G. Xiong, Argonne National Laboratory
C.Y. Han, Argonne National Laboratory
J.P. Birrell, Argonne National Laboratory
G.A. Willing, Argonne National Laboratory
H.H. Wang, Argonne National Laboratory
J.N. Hryn, Argonne National Laboratory
M.J. Pellin, Argonne National Laboratory
Correspondent: Click to Email
Atomic layer deposition (ALD) utilizes a binary reaction sequence of self-saturating chemical reactions between gaseous precursor molecules and a solid surface to deposit films in a layer-by-layer fashion. These attributes make ALD an ideal method for applying very precise, conformal coatings over porous materials. In this presentation, we describe recent work exploring the ALD coating of two porous solids: anodic aluminum oxide (AAO) and silica aerogels. The AAO and silica aerogels have been successfully coated by ALD with a variety of oxide films including Al@sub2@O@sub3@, ZnO, TiO@sub2@, Y@sub2@O@sub3@ and V@sub2@O@sub5@ as well as several metals. These materials were characterized with a host of analytical techniques including SEM, TEM, EDX, AFM, XRD and BET surface area measurements. The ALD coated AAO materials are being employed as mesoporous catalytic membranes as well as size-specific separations membranes. To fabricate the catalytic membranes from the AAO templates, the pore diameter of the AAO membranes is first reduced to the 5-10 nm regime using Al@sub2@O@sub3@ ALD. Next, TiO@sub2@ ALD is used to deposit several monolayers of catalytic support material. Finally, the active V@sub2@O@sub5@ catalyst is deposited by ALD. The resulting nanostructured catalytic membranes show remarkable selectivity in the oxidative dehydrogenation of cyclohexane when compared to conventional powder catalysts. Silica aerogels have the lowest density and highest surface area of any solid material. Consequently, these materials serve as an excellent substrate for fabricating catalytic materials by ALD. In addition to their use as catalysts, the ALD modified aerogel materials have applications in hydrogen storage and production, chemical sensing, and optics. In this study, both thin film and monolithic aerogels were coated by ALD and the coating process was investigated as a function of the reactant exposures.