Trilayer graphene in both ABA (Bernal) and ABC (rhombohedral) stacking sequences is shown to exhibit intense infrared absorption from in-plane optical phonons. The phonon feature, lying at ~1580 cm(-1), changes strongly with electrostatic gating. For ABC-stacked graphene trilayers, we observed a large enhancement in phonon absorption amplitude, as well as softening of the phonon mode, as the Fe...

A theory for the relaxation rates of a test electron and electron temperature in quantum wires due to deformation, piezoelectric acoustical and polar optical phonon scattering is presented. We represent intraand inter-subband relaxation rates as an average of rate kernels weighted by electron wave functions across a wire. We exploit these expressions to calculate phonon emission power for elect...

GaN and AlN compounds have been proven useful in wide bandgap microelectronics and optoelectronics. Also properties of bulk GaN and AlN have been studied extensively. However, many characteristics of AlGaN/GaN superlattices are not well known. In particular, the properties of phonons have not been determined. In order to determine phonon properties, this study measured infrared reflectivity spe...

Phonons – quanta of crystal lattice vibrations – reveal themselves in all electrical, thermal and optical phenomena in materials. Nanostructures open exciting opportunities for tuning the phonon energy spectrum and related properties of materials for specific applications. A recent advent of graphene and quasi two-dimensional materials increased the possibilities for controlled modification of ...

Recent studies of the surface dynamics of Al(001) and Cu(111) based on density functional perturbation theory have substantiated the existence of subsurface optical phonon resonances of all three polarizations, thus confirming early predictions of the embedded-atom method. The hybridization of the shear-vertical optical resonance with the longitudinal acoustic phonon branch accounts for the ubi...

Correlated transient absorption and atomic force microscopy (AFM) measurements have been performed for monolayer graphene, both free-standing and supported on a glass substrate. The AFM images allow us to locate regions of the suspended graphene. The transient absorption traces show a fast instrument response limited decay, followed by a slower intensity dependent decay. The fast decay is assig...

With an eye on dust particles immersed into an ionized gas, we study the effect of a negative charge on the scattering of light by a dielectric particle with a strong transverse optical phonon resonance in the dielectric constant. Surplus electrons alter the scattering behavior of the particle by their phonon-limited conductivity in the surface layer (negative electron affinity) or in the bulk ...

Using the Kubo linear response formalism, we study the effects of intrinsic graphene optical and surface polar phonons (SPPs) on the optical conductivity of doped graphene. We find that inelastic electron-phonon scattering contributes significantly to the phonon-assisted absorption in the optical gap. At room temperature, this midgap absorption can be as large as 20–25% of the universal ac cond...

The phonon-assisted interband optical absorption spectrum of silicon is calculated at the quasiparticle level entirely from first principles. We make use of the Wannier interpolation formalism to determine the quasiparticle energies, as well as the optical transition and electron-phonon coupling matrix elements, on fine grids in the Brillouin zone. The calculated spectrum near the onset of indi...

Chunxiao Cong,1 Jeil Jung,2,3,4 Bingchen Cao,1 Caiyu Qiu,1 Xiaonan Shen,1 Aires Ferreira,3,4,5 Shaffique Adam,3,4 and Ting Yu1,3,4,* 1Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore 2Department of Physics, University of Seoul, Seoul 130-743, Korea 3Department of Physics, Faculty of Science, National Univer...