Oxide and Chalcogenide Nanostructures
Hongkun Park
Department of Chemistry and Chemical Biology and Department of Physics, Harvard
University
Metal oxides and chalcogenides exhibit many properties beyond those of
simple metals and semiconductors, including ferroelectricity, charge-density-wave
properties, colossal magnetoresistivity, and high- TC superconductivity, and have
attracted considerable attention from engineering communities as possible candidates
for new technologies.
From the fundamental scientific standpoint, however, these materials present unique
challenges: due to their complex structures and the extreme sensitivity to the doping
levels, the controlled preparation of high-quality materials remains difficult. Moreover,
the physics behind their unique behaviors is not properly understood.
In this presentation, I will discuss a research effort in my group that aims to address this
question by developing general synthetic methods for preparing metal-oxide and
chalcogenide nanostructures and by probing the size-dependent evolution of their
properties at the individual nanostructure level. Specifically, I will discuss three
examples: (1) the synthesis of VO2 nanowires and the characterization of their Mott
metal-insulator transition, (2) the synthesis of GeTe nanowires and the characterization
of size scaling of their phase- change behavior, and (3) the fabrication of singlenanocrystal transistor incorporating individual CdSe nanocrystals and nanowires and the
characterization of electroluminescence and photoconductivity of these devices.