THE UNIVERSITY OF TEXAS AT AUSTIN • COCKRELL SCHOOL OF ENGINEERING. DEPARTMENT OF CHEMICAL ENGINEERING

Ekerdt, John G. Ph.D.

Dick Rothwell Endowed Chair in Chemical Engineering
Associate Dean for Research in Engineering

Research Areas: Advanced Materials, Polymers & Nanotechnology                                                  and Energy

Research Presentation for Prospective Graduate Students 

Educational Qualifications

Ph.D., Chemical Engineering, University of California Berkeley (1979)
B.S., Chemical Engineering, University of Wisconsin (1974)

Focus

Surface, growth and materials chemistry of metal, dielectric, ferroelectric, and polymer films and silicon nanostructures.  Kinetics and chemistry of biomass conversion to hydrocarbon products.

Figure 1: We are exploring passivation of surface nonradiative recombination centers on silicon nanoparticles using D2 and ND3 cracked over a heated filament, and thermally adsorbed ND3.  The filament generates a flux of D and NDx that adsorb on the surface, bond with the silicon atoms, and rearrange the Si-Si surface and Si-Si back bonds.  Quantum confined photoluminescence (PL) is realized over nanocrystals when enough atomic D is supplied to fully passivate the dangling bonds and eliminate the reconstructed surface bonds.

Figure 2: We study the growth of dielectric films using atomic layer deposition and ways to stabilize the amorphous phase and retain the high dielectric constant in the films by incorporating different elements into periodic or nanolaminate structures.  Studies incorporating La, Ta and Al have led to general design principles that can be used to guide the manufacture of high-k dielectrics that can be used in future electronic devices.

Research

The focus of my research is on the surface, growth and materials chemistry of metal, dielectric, ferroelectric, and polymer thin films, and of silicon nanostructures, and on the kinetics and chemistry of lignin depolymerization.  The former programs are motivated by applications in electronic materials and sensors.  The research programs are highly interdisciplinary and involve collaborations with faculty in chemical engineering, physics and electrical engineering, and researchers in industry.

Metal films find applications in sensors, optics and microelectronics, and as the critical dimensions or size of the applications and systems decrease, the metal film’s thickness will decrease to tens of atomic diameters at most and must have a specific microstructure.  Our program seeks to describe how films form, with an emphasis on nucleation and island coalescence, the evolution of interfacial layers that bind the film to the substrate, how properties of bulk materials scale with thickness, and precisely how short range order is preserved as the film thickness approaches thicknesses that are ten atomic diameters.

The research on silicon alloy nanoparticle growth chemistry on dielectric surfaces seeks to understand how to grow nanoparticles of a particular diameter and density, and how to precisely position these nanoparticles on the surface.  We also explore the surface chemistry of the nanoparticles to control their optical properties.  We have explored the chemistry and kinetics of nanoparticle growth in detail on silicon dioxide and find the nucleation is controlled by defects in the oxide surface; our current focus is to determine the chemical nature of defects on silicon dioxide and more generally on additional, technically relevant dielectric surfaces.

The research on dielectric and ferroelectric films seeks to understand the chemical reactions responsible for atomic layer deposition growth and the interfacial reactions responsible for forcing the films to remain amorphous or to grow in a crystalline form.  Studies with hafnia are exploring atomic layer deposition growth of periodic structures in which ions, such at La, Al and Ta, are incorporated to delay the onset of crystallization temperature and stabilizing the amorphous phase.  Studies with ferroelectrics explore homoepitaxy and heteroepitaxy of perovskite films using molecular beam epitaxy and atomic layer deposition and the role of the growth surface termination and methods to enhance wetting/spreading to realize two dimensional epitaxial growth and control the properties in the ferroelectric layer.

Lignin is one of the major components of lignocellulosic biomass and its resilience towards chemical attack is one of the major hurdles for biomass processing. Our work explores acid catalyzed routes to hydrolysis of the aryl ether oxygen bonds that comprise the backbone of lignin and deoxygenation catalysis.  Studies employ acidic ionic liquids, inorganic acids and metal chlorides for the hydrolysis reactions, and supported metals for the deoxygenation reactions – all in ionic liquid media, and seek to develop the kinetics and reaction pathways of lignin depolymerization.

Awards & Honors

Fellow of the American Institute of Chemical Engineers (2006)
Joe J. King Professional Engineering Achievement Award, College of Engineering, University of Texas (2005)
Hamilton Book Awards, Runner-up for Chemical Reactor Analysis and Design Fundamentals, University Co-op Society (2003)
Charles M. A. Stine Award in Materials Science and Engineering, American Institute of Chemical Engineers (2001)
Phi Kappa Phi Award for Dedicated Service in the Promotion of Excellence in Higher Education (1997)
Dick Rothwell Endowed Chair in Chemical Engineering (2001)
Chemical Engineering Department Teaching Award (1994)
Z. D. Bonner Professorship in Chemical Engineering (1991-2001)
Quantum Chemical Corporation Endowed Fellow in Engineering (1990-91)
Laurence E. McMakin Centennial Fellow in Chemical Engineering (1983-90)
Best Fundamental Paper, South Texas Section of AIChE (1980)
The University of Texas at Austin Engineering Foundation Faculty Excellence Award (1980, 1983, 1987, 1993)
Outstanding Young Member Award, 1984, South Texas Section of AIChE
Outstanding Engineering Teaching by an Assistant Professor, University of Texas (1985)

Selected Publications

• Chemistry of Silicon Nanocrystal Surfaces Exposed to Ammonia, (N. Salivati, N. Shuall, J. McCrate, J. G. Ekerdt), Journal of Physical Chemistry C 114, 16924-16928 (2010).
• Effect of surface chemistry on quantum confinement and photoluminescence from ammonia-passivated silicon nanocrystals (N. Salivati, N. Shaull, J. J. McCrate, J. G. Ekerdt) Journal of Physical Chemistry Letters 1, 1957-1961 (2010).
• Sub-nanoscale Lanthanum Distribution in Lanthanum-incorporated Hafnium Oxide Thin Films Grown Using Atomic Layer Deposition (T. Wang, J. G. Ekerdt), Chemistry of Materials 22, 3798-3806 (2010).
• On the Nature and Behavior of Li Atoms in Si: A First Principles Study (Hyunwoo Kim, Eun Kyoung, Gyeong S. Hwang, John G. Ekerdt, Chia-Yun Chou) J. Physical Chemistry C 114, 17942-17946 (2010).
• Cleaving the β-O-4 bonds of lignin model compounds in an acidic ionic liquid, 1-H-3-methylimidazolium chloride: an optional strategy for the degradation of lignin (S. Jia, B. J. Cox, X. Guo, Z. Conrad Zhang, J. G. Ekerdt), ChemSusChem 3, 1078-1084 (2010).
• Hydrolytic cleavage of β-O-4 ether bonds in lignin model compounds in an ionic liquid with metal chlorides (Songyan Jia, Blair J. Cox, Xinwen Guo, Z. Conrad Zhang, John G. Ekerdt) Industrial & Engineering Chemistry Research 50, 849-855 (2011).