Chemistry People: Faculty by Name:

Research Interests:

Physical Chemistry of Semiconductor Nanocrystals
Optical, electrical, and thermodynamic properties of a new class of materials, semiconductor nanocrystals, are investigated.

Semiconductor nanocrystals are a new type of material with properties that vary remarkably as a function of the size. These crystallites represent a limit to the miniaturization of the features in electronic circuits. In the size regime of a few nanometers, the boundaries of the crystallite are comparable in dimension to the wavelength of electrons in the extended solid. As a consequence, the optical and electrical properties of the nanocrystals are dominated by quantum effects not seen in today's electrical devices. The large number of atoms in a crystallite, compared to a molecule, and the absence of long range order, mean that these questions present serious challenges to theory as well as to experiment. In addition, the number of atoms present on the surface, as opposed to the interior of the nanocrystals, is very large, so that the surface science of nanocrystals is a rich area of investigation.

Nanocrystals, prepared initially for their electro-optic properties, also offer an opportunity to study long-standing issues concerning phase transitions. A phase transition occurs when the length scale of fluctuations between two stable states of the system diverges. Thus, in principle phase transitions are only defined for extended systems. Is there a size below which abrupt temperature of pressure induced structural transformation must be viewed as isomerizations rather than phase transitions

Biography:

Paul Alivisatos went to the University of Chicago, where he received a Bachelor's degree in Chemistry with Honors in 1981. He attended graduate school at the University of California, Berkeley, where he worked under the supervision of Charles Harris. His Ph.D. thesis concerned the photophysics of electronically excited molecules near metal and semiconductor surfaces. In 1986, he went to AT&T Bell Labs where he worked with Louis Brus as a postdoctoral, and it was at this time that he first became involved in research related to Nanotechnology. In 1988, he joined the faculty of the University of California, Berkeley, as an Assistant Professor of Chemistry. He was promoted to Associate Professor in 1993 and to Professor in 1995. He was appointed Chancellor's Professor of the University of California, Berkeley for the period 1998-2001. Additionally, in 1999 he was appointed Professor in the Materials Science and Mineral Engineering Department. He has received the Presidential Young Investigator Award, the Alfred P. Sloan Foundation fellowship, the ACS Exxon Solid State Chemistry Fellowship, the Coblentz Award, the Wilson Prize at Harvard, DOE Awards for Outstanding Scientific Accomplishment in Materials Chemistry (1994) and for Sustained Outstanding Research in Materials Chemistry (1997), the Materials Research Society Outstanding Young Investigator Award and the ACS Award in Colloid and Surface Chemistry (2004). He is a Fellow of both the American Physical Society and the American Association for the Advancement of Science. In 2004 he was elected into the National Academy of Sciences and the National Academy of Arts. He is the Editor of the American Chemical Society Journal, Nano Letters, and is Associate Editor of the Annual Review of Physical Chemistry. He serves on the Editorial Advisory Boards of the Accounts of Chemical Research (American Chemical Society) and the Virtual Journal of Nanoscale Science and Technology (American Physical Society). He is a senior member of the technical staff at the Lawrence Berkeley National laboratory, where he has been appointed Associate Laboratory Director for Physical Sciences and where he also serves as Director of the Materials Sciences Division. He has served as a member of the Defense Sciences Study Group, and on panels of the Defense Science Board and the National Research Council, and is currently a member of the Department of Energy Council on Materials Sciences. His research concerns the structural, thermodynamic, optical, and electrical properties of nanocrystals.