We are conducting research to understand acoustic wave propagation in nanostructured materials, in terms of thin films, nanocrystallites, and low dimensional systems. Development in micro- and nano-fabrication technologies has enabled exciting advances in photonic and nano-electronic devices. As we push state-of-the-art fabrication and measurement capability to yet smaller domains, approaching nanometer length scales, we expect similar progress can be made in the phononic properties of materials and hence to control the basic phonon transport and scattering properties of materials. This in term will impact a number of electronic and optical properties of nanostructured materials as electron-phonon interactions are the dominant mechanism mediating relaxation and energy transport phenomena in semiconductors. Our goal is to understand (thermal) phonon transport and scattering as the size of the structure or scattering centers become comparable to those of thermal phonon wavelength and/or phonon mean free path. Possible applications in thermoelectrics will be explored. The research work involves nanofabrication to design and prepare samples, such as thin film deposition (electron-beam evaporation, sputtering, plasma-enhanced chemical vapor deposition), photolithography, electron beam lithography, reactive ion etching, and wet chemical etching. The work also offers opportunity to make thermal, elastic, electric, magnetic, and thermoelectric measurements in cryogenic temperatures to as low as 20 mK.

 

key words

Thermal conductivity; Internal friction; Nanocrystallites; Thin films; Nanofabrication; Phonons; Acoustics; Thermoelectrics; Nanomechanics;

Citizenship:  Open to U.S. citizens and permanent residents

Level:  Open to Postdoctoral applicants