University of Tennessee Physics

Dr. Hanno Weitering

Professor and
UT/ORNL Joint Faculty Member

Ph.D., University of Groningen, 1991

Office: 406B Nielsen Physics Building
Phone: 865-974-7841
Fax: 865-974-7843
hanno@utk.edu


CONDENSED MATTER EXPERIMENT

(See also Dr. Weitering's Group Page)

Surface Science

Surface science is one of the forefront areas within the larger field known as condensed matter physics or, more broadly, the materials sciences. Surface Science has two principal goals: 1) the exploration and understanding of the exotic structural, electronic and vibrational properties of pristine crystal surfaces, adsorbates or ultrathin film materials and 2) the use and creative manipulation of this knowledge to produce new solid state structures. This area impacts fields as diverse as chemical catalysis, electronic devices and laser optics.

In our group, we are exploring the physics of semiconductor surfaces and metal/semiconductor interfaces. As solid state device structures become smaller and smaller, the properties of the semiconductor surface or interface naturally become more and more important. For instance, in order to understand the macroscopic current-voltage characteristics of a metal-semiconductor junction, one needs to explore the microscopic origin of interface states. Possible future applications of quantum wires as interconnects in nanoscale electronic devices require new insights into localization phenomena and electrical conductivity in ultrathin films.

Our approach is at the most fundamental level and is intended to provide the underpinnings for understanding and control of surface phenomena. We use a large variety of experimental methods to explore the structural and electronic properties of semiconductor surfaces and metal-semiconductor interfaces. We can "see" individual atoms and image the surface charge density with a scanning tunneling microscope. We measure the two-dimensional band dispersion of surface state electrons with photoemission using synchrotron radiation. Spectroscopic data are correlated with macroscopic observables such as electrical conductivity and magnetization. This link between the microscopic world of atoms and the macroscopic world of devices is the core of our research program and is aimed at bridging the gap between fundamental surface physics and solid state electronics. We are currently constructing a unique apparatus capable of measuring the magnetic susceptibility of submonolayer amounts of magnetic atoms. Each of these experimental endeavors has been undertaken in close collaboration with theory so as to provide the broadest level of understanding.

Brief Vita

Hanno Weitering earned a M.S. degree in Inorganic Chemistry (1986) and a Ph.D. degree in Mathematics and Natural Sciences (1991) at the University of Groningen in The Netherlands. He spent two years as a distinguished Benjamin Franklin Fellow at the University of Pennsylvania before joining the physics faculty at the University of Tennessee in 1993. Weitering is also affiliated with Oak Ridge National Laboratory through the UTK/ORNL Joint Faculty program. His publication record includes more than 40 papers in refereed journals. He received the DSM prize for Chemistry and Technology in 1991 and held a chair professor position at the Delft University of Technology in The Netherlands from 2000 until 2001.

Selected Publications

  1. "Surface conductance near the order-disorder phase transition on Si(100)," K Yoo and H.H. Weitering, Phys. Rev. Lett. 87, 026802 (2001).
  2. "Isolation of a Metallic Si(111)7x7 Surface Reconstruction via Separation by Implanted Oxygen," M. Noh, G.E. Jellison Jr., F. Namavar and H.H. Weitering, Appl. Phys. Lett. 76, 733-735 (2000).
  3. "Defect-mediated condensation of a charge density wave," H.H. Weitering, J.M. Carpinelli, A.V. Melechko, J. Zhang, M. Bartkowiak, and E.W. Plummer, Science 285, 2107-2110 (1999).
  4. "Theory of the "honeycomb chain-channel" reconstruction of Si(111)3x1," S.C. Erwin and H.H. Weitering, Phys. Rev. Lett. 81, 2296-2299 (1998).
  5. "Mott insulating ground state on a triangular surface lattice," H.H. Weitering, X. Shi, P.D. Johnson, J. Chen, N.J. DiNardo, and K. Kempa, Phys. Rev. Lett. 78, 1331-1334 (1997).
  6. Surface charge ordering transition: (alpha)-phase of Sn/Ge(111), J.M. Carpinelli, H.H. Weitering, M. Bartkowiak, R. Stumpf and E.W. Plummer, Phys. Rev. Lett. 79, 2859 (1997).
  7. "Direct observation of a surface charge density wave," J.M. Carpinelli, H.H. Weitering, E.W. Plummer and R. Stumpf, Nature 381, 398-400 (1996); cover article.
  8. "Atomic structure dependent Schottky barrier at epitaxial Pb/Si(111) interfaces," D.R. Heslinga, H.H. Weitering, D.P. van der Werf, T.M. Klapwijk and T. Hibma, Phys. Rev. Lett. 64, 1589-1592 (1990).