Atomic Layer Deposition

A joint initiative of the Energy Systems and Materials Science Divisions

Welcome to the homepage of the Atomic Layer Deposition (ALD) Research Program at Argonne National Laboratory.  The program is a joint initiative of the Materials Science and Energy Systems Divisions that combines basic and applied sciences.  We are expanding ALD into new fields and deposition platforms, and developing ALD thin film technologies  that address a wide variety of our nation’s energy challenges. In particular, we are focusing our attention on solar cells, catalysis, solid state lighting, separation membranes, and superconductivity.

Overview of ALD

Atomic layer deposition (ALD) is a thin film growth technique that offers the unique capability to coat complex, 3-dimensional objects with precise, conformal layers.  In addition, ALD allows atomic-level control over the thickness and composition of the deposit.

ALD uses alternating, saturating reactions between gaseous precursor molecules and a substrate to deposit films in a layer-by-layer fashion. By repeating this reaction sequence in an ABAB… fashion, films of virtually any thickness, from atomic monolayers to micrometer dimensions, can be deposited with atomic layer precision.  This alternating reaction strategy eliminates the line-of-sight or constant-exposure requirements that limit conventional methods such as physical- or chemical-vapor deposition.

As an example, consider the following binary reaction sequence for the ALD of Al2O3:  

ALD can deposit a wide variety of materials including oxides, nitrides, sulfides and metals.  An integral component of the Argonne ALD research program is to invent new binary reaction sequence chemistries that extend the range of useful thin film materials.

Our Facilities

We currently have three bench-scale ALD thin film deposition reactor systems that were designed and constructed at Argonne.  These unique reactor systems are very flexible and allow us to deposit a wide range of materials with atomic level precision onto nearly any substrate.  We deposit ALD materials onto nano-porous templates such as anodic aluminum oxide (AAO) membranes and low-density aerogels, catalytic supports, and tubes, (up to one meter in length, 10 cm in diameter).  We are also designing larger, application specific reactors.  To enable detailed studies of new ALD chemistries, our bench-scale reactor systems are equipped with in-situ measurement capabilities including quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS).  We also developed GaPO4 sensors for improved diagnostics.  In addition, we have a full range of thin-film measurement tools (AFM, XPS, SIMS, WVASE, XRF, etc.)  Our ALD research benefits enormously from ready access to Argonne’s remarkable suite of measurement facilities such the Advanced Photon Source, the Center for Nanoscale Materials and the Electron Microscopy Center.

Research

Primary Focus Projects

• Solar Cells (In2O3, SnO2, TiO2) – Transparent conducting oxide layers as well as semiconducting oxide films are deposited using ALD to form novel light-harvesting devices.
• Novel Selective Oxidation Catalysts:  We are developing new techniques for the manufacture of catalysts by ALD for the selective oxidative dehydrogenation of alkanes, for example, ethane to ethylene, or propane to propylene.  As one template for these catalysts, we are coating commercial silica gel powders comprised of ~100 micron diameter silica beads that are agglomerates of ~10 nm particles.  These silica gel beads possess a very high surface area and pose unique challenges for coating.
• Nanostructured Catalytic Membranes: We are synthesizing, characterizing and testing nanostructured catalytic membranes fabricated using ALD.  As a starting template, we use anodic aluminum oxide (AAO) membranes comprised of hexagonal arrays of uniform pores.  We coat the inner surfaces of the pores with ALD Al2O3 to reduce the pore diameter.  Next, we deposit a catalytic support layer.  Finally, we deposit the active catalyst.
• Nanoporous Separations Membranes: We coat the interior of AAO pores with atomic level precision using atomic layer deposition (ALD) techniques.  Next, using ALD of selected materials, the chemical nature of the pore wall coating is tuned to allow further specificity during separations.  The result is a nanoporous separation membrane (NSM) with excellent molecular size and chemistry selectivity.
• High Temperature Superconductors – (YBa2Cu3O7) HTS Ceramic materials are deposited conformally on conducting substrates to enable the efficient fabrication of second generation coated conductors.
• Solid Oxide Electrolysis Cells – Thin films of yttria-stabilized zirconia (YSZ) are deposited by ALD yielding dense, conformal ion-conducting layers to enable high efficiency, low cost solid oxide electrolysis cells for the production of hydrogen fuel from heat.
• Solid State Lighting – We are fabricating novel transparent conducting electrodes for organic LEDs.  We assemble magnetic micro- and nanoparticles into self-organized two dimensional patterns of highly interconnected chains using an external alternating magnetic field.  Next, we apply thin, transparent conducting oxide layers by ALD to stabilize and functionalize the nanoparticle arrays.

Additional Projects:

• Aerogels – Aerogels due to their extremely low density, low thermal conductivity, and high specific surface area have found diverse applications in sensing, catalysis, aerospace and high-energy physics.  By conformally coating aerogels using atomic layer deposition (ALD), we can both precisely define the surface chemical properties and dramatically enhance the physical properties of the aerogels to greatly extend their utility.  Carbon aerogels coated by ALD tungsten have applications as spallation targets for the production of radioactive ion beams.
• Hydrogen Economy – (Pd) Nanoporous scaffolds are coated with ultra-thin metal layer for efficient hydrogen production, storage and sensing.
• Hermetic Coatings – (Y2O3, ZrO2, Al2O3) Conformal amorphous layers are deposited on all surfaces fully encapsulate a device for medical implantation, or to be used in corrosive environments.
• Chemical Sensors – (ZnO, SnO2)  Nanoporous anodic alumina and aerogel templates are coated with ultra-thin conducting oxide layers to form chemical sensors.
• Optical Nanosensors – Noble metal nanoparticles coated with dielectric films act as optical biosensors and chemosensors based on the localized surface plasmon resonance (LSPR) effect. Consequently, the optical properties of LSPR sensors can be tailored using ALD coatings.  (Collaboration with Northwestern University)

Publications and Presentations

Publications

• J. W. Elam, A. B. F. Martinson, M. J. Pellin, and J. T. Hupp, “Atomic Layer Deposition of In₂O₃ Using Cyclopentadienyl Indium: A New Synthetic Route to Transparent Conducting Oxide Films”, Chemistry of Materials, 18, 3571-3578, (2006).

• J. W. Elam,  J. A. Libera, M. J. Pellin, A. V. Zinovev, J. P. Greene, and J. A. Nolen, “Atomic layer deposition of W on nanoporous carbon aerogels”, Appl. Phys. Lett., 89, 053124, (2006).

• G. Xiong, J. W. Elam,  H. Feng, C. Y. Han, H.–H. Wang, L. E. Iton, L. A. Curtiss, M. J. Pellin, M. Kung, H. Kung, and P. C. Stair,  “Effect of Atomic Layer Deposition Coatings on the Surface Structure of Anodic Aluminum Oxide Membranes”,  J. Phys. Chem. B., 109 (29), 14059-14063 (2005).

• J. W. Elam and M. J. Pellin, “GaPO4 Sensors for Gravimetric Monitoring during Atomic Layer Deposition at High Temperatures”, Anal. Chem., 77, 3531 (2005).

• M. J. Pellin, P. C. Stair, G. Xiong, J. W. Elam, J. Birrell, L. Curtiss, S. M. George, C. Y. Han, L. Iton, H. Kung, M. Kung, H.–H. Wang, “Mesoporous Catalytic Membranes: Synthetic Control of Pore Size and Wall Composition”, Catalysis Letters, 102 (3-4), 127-130 (2005).

• V. Whitney, J. W. Elam, S. Zou, A. V. Zinovev, P. C. Stair, G. C. Schatz and R. P. Van Duyne, “Localized Surface Plasmon Resonance Nanosensor: A High-Resolution Distance Dependence Study using Atomic Layer Deposition”, J. Phys. Chem. B, 109 (43), 20522-20528, (2005).

• S. O. Kucheyeva, J. Biener, Y. M. Wang, T. F. Baumann, K. J. Wu, T. van Buuren, A. V. Hamza, and J. H. Satcher, Jr., J. W. Elam and M. J. Pellin, “Atomic Layer Deposition of ZnO on Ultralow-Density Nanoporous Silica Aerogel Monoliths”, Appl. Phys. Lett., 86, 083108 (2005).

Posters from the ALD 2005 Conference

• J. W. Elam, P. W. Klamut, J. E. Gerbi, G. Xiong, C. Y. Han, H. H. Wang, J. N. Hryn, M. J. Pellin, "Nucleation, Growth and Crystallization of ALD Catalytic Oxide Layers."

• Jeffrey W. Elam, Alex Zinovev, Catherine Y. Han, Hau H. Wang, Ulrich Welp,
  John N. Hryn and Michael J. Pellin, "Atomic Layer Deposition of Palladium Films on Al2O3 Surfaces."

• Jeffrey W. Elam and Michael J. Pellin, "GaPO4 Sensors for Gravimetric Monitoring During Atomic Layer Deposition at High Temperatures."

Collaborators

• Argonne Chemistry Division
• Argonne Chemical Engineering Division
• Argonne Physics Division
• Northwestern University Department of Chemistry
• Lawrence Livermore National Laboratory
• University of Nevada, Las Vegas Department of Chemistry
• University of Notre Dame, Department of Electrical Engineering

Contacts

“For further information about atomic layer deposition at Argonne, please contact us at aldfilms@anl.gov or contact

• Jeffrey Elam
• Michael Pellin