Carbon nanotubes and graphene are candidate materials for nanoscale electronic devices. Both materials show weak acoustic phonon scattering and long mean free paths for low-energy charge carriers. However, high-energy carriers couple strongly to optical phonons, which leads to current saturation and the generation of hot phonons. A non-equilibrium phonon distribution has been invoked to explain...

Phonons are quanta of lattice vibrations. They play an important role in various phenomena seen in solid state. The physics of phonons and phenomena associated with them are explored.

We report on the time-resolved observation of coherent optical phonons in GaAs by the Franz-Keldysh effect. This effect leads to a modulation of the optical interband transitions with a nonlinear dependence on the macroscopic electric field associated with the coherent phonons. We find that the nonlinear electro-optic effect forms a far more efficient detection mechanism for coherent phonons th...

The analytic expression for the Hall Coefficient (HC) caused by the confined electrons in the presence of a strong electromagnetic wave (EMW) including the effect of phonon confinement in rectangular quantum wires (RQWs) is calculated by using the quantum kinetic equation for electrons in the case of electron optical phonon scattering. It is because the expression of the HC for the confined pho...

Non-metallic crystalline materials conduct heat by the transport of quantized atomic lattice vibrations called phonons. Thermal conductivity depends on how far phonons travel between scattering events-their mean free paths. Due to the breadth of the phonon mean free path spectrum, nanostructuring materials can reduce thermal conductivity from bulk by scattering long mean free path phonons, wher...

Heat transfer across metal-dielectric interfaces involves transport of electrons and phonons accomplished either by coupling between phonons in metal and dielectric or by coupling between electrons in metal and phonons in dielectric. In this work, we investigate heat transfer across metal-dielectric interfaces during ultrafast-laser heating of thin metal films coated on dielectric substrates. B...

We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, ~65% at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carryin...

We present the program MCAnScat which simulates propagation of beams of down-converting phonons in anisotropic cubic and isotropic media containing point mass defects. It is assumed that the excitation the phonon subsystem is low-level. The program produces time-of-flight spectrograms and phonon energy and quasi-momentum focusing patterns for samples having the form of a rectangular parallelepi...

in this study, bio-based carbon nanotubes (cnts) have received considerable research attention due to their comparative advantages of high level stability, simplistic use, low toxicity and overall environmental friendliness. new potentials for improvement in heat transfer applications are presented due to their high aspect ratio, high thermal conductivity and special surface area. phonons have ...

The existences of light and fermions are two big mysteries in nature. The mysteries are so deep that the questions like, “What are light and fermions?”, “Where do light and fermions come from?”, “Why do light and fermions exist?”, are regarded by many people as philosophical or even religious questions. To appreciate the physical significance those questions let us ask three simpler questions: ...