Phononics
Studying phonon transport at nanoscale
The goal of the project is to study the propagation of phonons at nanoscales where the average distance between the boundaries of the materials is comparable or less than the mean free path of phonons, usually referred to as ballistic regime. It can be achieved by using phononic crystals, nanowires, and thin membranes. Ballistic phonons are extremely interesting as they can result in a completely new thermal behavior of materials and boost their thermal or thermoelectric properties. Such properties can help to develop more energy-efficient electronics and to extract heat from nanosized objects.
Sergei Gluchko
Researcher in nanophotonics
Publications
Cross-plane thermal conductivity in amorphous Si/SiO2 superlattices
Here, we experimentally demonstrate thermal transport in amorphous atomic-scale superlattices that can provide lower thermal conductivity value than amorphous limit.
Thermal conductivity reduction in a silicon thin film with nanocones
We propose a cost-effective, large-area, and maskless nanofabrication method that creates external nanocones on the silicon surface while preserving its interior. Our experiments show that these nanocones reduce the thermal conductivity of thin silicon membranes by more than 40%.
Probing ballistic thermal conduction in segmented silicon nanowires
Here, we experimentally probed ballistic thermal transport at distances of 400–800 nm and temperatures of 4–250 K. Measuring thermal properties of straight and serpentine silicon nanowires, we found that at 4 K heat conduction is quasi-ballistic with stronger ballisticity at shorter length scales.
On the reduction and rectification of thermal conduction using phononic crystals with pacman-shaped holes
We measure the thermal conductivity of silicon phononic crystals with asymmetric holes at room and liquid helium temperatures and study the effect of thermal rectification, phonon boundary scattering, neck transmission, and hole positioning.
Quasi-ballistic heat conduction due to Lévy phonon flights in silicon nanowires
Here, we experimentally demonstrate quasi-ballistic heat conduction in silicon nanowires (NWs). We show that the ballisticity is the strongest in short NWs at low temperatures but weakens as the NW length or temperature is increased.
