Intense electron-phonon scattering near the peak electric field in a semiconductor device results in nanometer-scale phonon hotspots. Past studies have argued that ballistic phonon transport near such hotspots serves to restrict heat conduction. We reexamine this assertion by developing a new phonon transport model. In a departure from previous studies, we treat isotropic dispersion in all phon...

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 single-layer black phosphorus is characteristic for its puckered structure, which has led to distinct anisotropy in its optical, electronic, and mechanical properties. We use the non-equilibrium Green's function approach and the first-principles method to investigate the thermal conductance for single-layer black phosphorus in the ballistic transport regime, in which the phonon-phonon scatt...

We review our recent results obtained on an AlN/GaN-based high-electron-mobility transistor. The temperature of the electrons drifting under a relatively-high electric field is significantly higher than the lattice temperature (i.e., the hot electrons are generated). These hot electrons are produced through the Fröhlich interaction between the drifting electrons and long-lived longitudinal-opti...

In the past five years enormous progress has been made in the ab initio calculations of the optical response of electrons in semiconductors. The calculations include the Coulomb interaction between the excited electron and the hole left behind, as well as local field effects. However, they are performed under the assumption that the atoms occupy fixed equilibrium positions and do not include ef...

In this work, we compute the phonon properties of carbon nanotube using finite difference method and DFPT approach separately for comparison. We found that both methods produce very similar phonon frequencies near the G-point. However, in the high frequency range, the optical phonons from both methods differ significantly. We attribute this difference to the variation of accuracies in atomic fo...

We investigated temperature dependent optical conductivity spectra of La7/8Sr1/8MnO3. Its phonon bending mode starts to be splitted near a structural phase transition temperature. With further cooling, strength of a midinfrared small polaron peak, which is located at 0.4 eV, becomes increased. These temperature dependent changes in the phonon spectra and the polaron absorption peaks were explai...

The magnetic freeze-out of two-dimensional electrons {the formation of a Wigner crystal or disordered dielectric state) is shown to stimulate acousticaland optical-phonon emissions in the course of their radiative recombination with an acceptor-bound hole. This allows us to expect an appearance of the corresponding phonon replicas in the spectra taken at the long time-delayed tail of the time-r...

A series of first principles calculations have been carried out in order to discuss electronic structure, phonon dynamics, structural instabilities and the nature of martensitic transformations of the Heusler alloys Ni2Mn(Ga, Ge, Al) and Co2Mn(Ga, Ge). The calculations show that besides electronic pecularities like Fermi–surface nesting, hybridizing optical and acoustic phonon modes are importa...

We report on Raman scattering by phonon pairs in GaN films grown on sapphire substrates by plasma-enhanced molecular beam epitaxy. The first order data are consistent with results obtained from GaN bulk crystals of the wurtzite structure. The Al and the much weaker E2 symmetry components of the second order scattering have been identified. Two-phonon spectra are dominated by contributions due t...