Статті в журналах з теми "Phonon energy"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Phonon energy.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Phonon energy".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Dovlatova, Alla, and Dmitri Yerchuck. "Quantum Field Theory of Dynamics of Spectroscopic Transitions by Strong Dipole-Photon and Dipole-Phonon Coupling." ISRN Optics 2012 (December 12, 2012): 1–10. http://dx.doi.org/10.5402/2012/390749.
Анотація:
Matrix-operator difference-differential equations for dynamics of spectroscopic transitions in 1D multiqubit exchange-coupled (para)magnetic and optical systems by strong dipole-photon and dipole-phonon coupling are derived within the framework of quantum field theory. It has been established that by strong dipole-photon and dipole-phonon coupling the formation of long-lived coherent system of the resonance phonons takes place, and relaxation processes acquire pure quantum character. It is determined by the appearance of coherent emission process of EM-field energy, for which the resonance phonon system is responsible. Emission process is accompanied by phonon Rabi quantum oscillation, which can be time-shared from photon quantum Rabi oscillations, accompanying coherent absorption process of EM-field energy. For the case of radio spectroscopy, it corresponds to the possibility of the simultaneous observation along with (para)magntic spin resonance, the acoustic spin resonance.
2
Zhao, Feng Qi, and Xiao Mei Dai. "Influence of Pressure on Polaron Energy in a Wurtzite GaN/AlxGa1-xN Quantum Well." Solid State Phenomena 288 (March 2019): 17–26. http://dx.doi.org/10.4028/www.scientific.net/ssp.288.17.
Анотація:
The influence of hydrostatic pressure on the polaron energy level in wurtzite GaN/AlxGa1-xN quantum well is studied by a Lee-Low-Pines variational method, and the numerical results of the ground state energy, transition energy and contributions of different phonons to polaron energy (polaron effects) are given as functions of pressurepand compositionx. The results show that the ground state energy and transition energy in the wurtzite GaN/AlxGa1-xN quantum well decrease with the increase of the hydrostatic pressurep, and increase with the increase of the compositionx. The contributions of different phonons to polaron energy with pressurepand compositionxare obviously different. With the increase of hydrostatic pressure, the contribution of half-space phonon, confined phonon and the total contribution of phonons of all branches increases obviously, while the contribution of interface phonon slowly increases. During the increase of the composition, the contribution of interface phonon decreases and the contribution of half-space phonon increases slowly, while the contribution of confined phonon and the total contribution of phonons increases significantly. In general, the electron-optical phonon interaction play an important role in electronic states of GaN/AlxGa1-xN quantum wells and can not be neglected.
3
Kang, Nam Lyong, and Sang Don Choi. "Projection-Reduction Approach to Optical Conductivities for an Electron-Phonon System and Their Diagram Representation." ISRN Condensed Matter Physics 2014 (April 7, 2014): 1–23. http://dx.doi.org/10.1155/2014/719120.
Анотація:
Utilizing state-dependent projection operators and the Kang-Choi reduction identities, we derive the linear, first, and second-order nonlinear optical conductivities for an electron system interacting with phonons. The lineshape functions included in the conductivity tensors satisfy “the population criterion” saying that the Fermi distribution functions for electrons and Planck distribution functions for phonons should be combined in multiplicative forms. The results also contain energy denominator factors enforcing the energy conservation as well as interaction factors describing electron-phonon interaction properly. Therefore, the phonon absorption and emission processes as well as photon absorption and emission processes in all electron transition processes can be presented in an organized manner and the results can be represented in diagrams that can model the quantum dynamics of electrons in a solid.
4
Jin, Jae Sik, and Joon Sik Lee. "Electron–Phonon Interaction Model and Prediction of Thermal Energy Transport in SOI Transistor." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 4094–100. http://dx.doi.org/10.1166/jnn.2007.010.
Анотація:
An electron–phonon interaction model is proposed and applied to thermal transport in semiconductors at micro/nanoscales. The high electron energy induced by the electric field in a transistor is transferred to the phonon system through electron–phonon interaction in the high field region of the transistor. Due to this fact, a hot spot occurs, which is much smaller than the phonon mean free path in the Si-layer. The full phonon dispersion model based on the Boltzmann transport equation (BTE) with the relaxation time approximation is applied for the interactions among different phonon branches and different phonon frequencies. The Joule heating by the electron–phonon scattering is modeled through the intervalley and intravalley processes for silicon by introducing average electron energy. The simulation results are compared with those obtained by the full phonon dispersion model which treats the electron–phonon scattering as a volumetric heat source. The comparison shows that the peak temperature in the hot spot region is considerably higher and more localized than the previous results. The thermal characteristics of each phonon mode are useful to explain the above phenomena. The optical mode phonons of negligible group velocity obtain the highest energy density from electrons, and resides in the hot spot region without any contribution to heat transport, which results in a higher temperature in that region. Since the acoustic phonons with low group velocity show the higher energy density after electron–phonon scattering, they induce more localized heating near the hot spot region. The ballistic features are strongly observed when phonon–phonon scattering rates are lower than 4 × 1010 s−1.
5
Jin, Jae Sik, and Joon Sik Lee. "Electron–Phonon Interaction Model and Prediction of Thermal Energy Transport in SOI Transistor." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 4094–100. http://dx.doi.org/10.1166/jnn.2007.18084.
Анотація:
An electron–phonon interaction model is proposed and applied to thermal transport in semiconductors at micro/nanoscales. The high electron energy induced by the electric field in a transistor is transferred to the phonon system through electron–phonon interaction in the high field region of the transistor. Due to this fact, a hot spot occurs, which is much smaller than the phonon mean free path in the Si-layer. The full phonon dispersion model based on the Boltzmann transport equation (BTE) with the relaxation time approximation is applied for the interactions among different phonon branches and different phonon frequencies. The Joule heating by the electron–phonon scattering is modeled through the intervalley and intravalley processes for silicon by introducing average electron energy. The simulation results are compared with those obtained by the full phonon dispersion model which treats the electron–phonon scattering as a volumetric heat source. The comparison shows that the peak temperature in the hot spot region is considerably higher and more localized than the previous results. The thermal characteristics of each phonon mode are useful to explain the above phenomena. The optical mode phonons of negligible group velocity obtain the highest energy density from electrons, and resides in the hot spot region without any contribution to heat transport, which results in a higher temperature in that region. Since the acoustic phonons with low group velocity show the higher energy density after electron–phonon scattering, they induce more localized heating near the hot spot region. The ballistic features are strongly observed when phonon–phonon scattering rates are lower than 4 × 1010 s−1.
6
Rodrigues, Ligia M. C. S., and Stenio Wulck. "q-Deformation and Energy Deficit in Liquid Helium Phonon Spectrum." Modern Physics Letters B 11, no. 07 (March 20, 1997): 297–301. http://dx.doi.org/10.1142/s0217984997000372.
Анотація:
We present an application of an ideal bosonic q-gas in a ν0 inequivalent representation to the phonons in 4 He and discuss the role of q-deformation as a possible mechanism to supply the energy deficit that forbiddens one-phonon decay into two phonons when the constant γ in the phonon anomalous dispersion relation (ωph = c0p(1 - γp2)) is positive.
7
Bin Mansoor, Saad, and Bekir Sami Yilbas. "Nonequilibrium cross-plane energy transport in aluminum–silicon–aluminum wafer." International Journal of Modern Physics B 29, no. 17 (June 23, 2015): 1550112. http://dx.doi.org/10.1142/s021797921550112x.
Анотація:
Transient phonon transport across cross-planes of aluminum–silicon–aluminum combined films is investigated and the Boltzmann transport equation is incorporated to formulate the energy transport in the combined films. Since electrons and phonons thermally separate in the thin aluminum film during heating, the Boltzmann equation is used separately in the electron and lattice subsystems to account for the energy transport in the aluminum film. Electron–phonon coupling is incorporated for the energy exchange between electron and lattice subsystems in the film. Thermal boundary resistance (TBR) is introduced at the interfaces of the silicon–aluminum films. In order to examine the ballistic contribution of phonons on the phonon intensity distribution in the silicon film, frequency-dependent solution of the Boltzmann equation is used in the silicon film and the film thickness is varied to investigate the size effect on the thermal conductivity in the film. It is found that equivalent equilibrium temperature of phonons remains high at silicon–aluminum interface because of the ballistic contribution of the phonons. Equivalent equilibrium temperature for the electron subsystem becomes higher than that corresponding to phonon temperature at the aluminum–silicon interface.
8
MATULIONIS, A., J. LIBERIS, L. ARDARAVIČIUS, J. SMART, D. PAVLIDIS, S. HUBBARD, and L. F. EASTMAN. "HOT-PHONON LIMITED ELECTRON ENERGY RELAXATION IN AlN/GaN." International Journal of High Speed Electronics and Systems 12, no. 02 (June 2002): 459–68. http://dx.doi.org/10.1142/s0129156402001381.
Анотація:
Microwave noise technique is applied to study energy dissipation in an AlN/GaN heterostructure containing a two-dimensional electron gas channel. Measurements of the dissipated power and the noise temperature are performed at 80 K lattice temperature in the electric field range up to 40 kV/cm. The energy relaxation time is found to decrease from 40 ps to 0.55 ps when the bias is increased. The experimental data are discussed in the electron temperature approximation assuming electron energy dissipation on optical phonons and hot-phonon effects. Dependencies of the hot-phonon number and the hot-phonon temperature on the hot-electron temperature are deduced. The frequency cutoff imposed by the limited energy dissipation through optical phonons is estimated.
9
Zhou, Jiawei, Bolin Liao, Bo Qiu, Samuel Huberman, Keivan Esfarjani, Mildred S. Dresselhaus, and Gang Chen. "Ab initio optimization of phonon drag effect for lower-temperature thermoelectric energy conversion." Proceedings of the National Academy of Sciences 112, no. 48 (November 16, 2015): 14777–82. http://dx.doi.org/10.1073/pnas.1512328112.
Анотація:
Although the thermoelectric figure of merit zT above 300 K has seen significant improvement recently, the progress at lower temperatures has been slow, mainly limited by the relatively low Seebeck coefficient and high thermal conductivity. Here we report, for the first time to our knowledge, success in first-principles computation of the phonon drag effect—a coupling phenomenon between electrons and nonequilibrium phonons—in heavily doped region and its optimization to enhance the Seebeck coefficient while reducing the phonon thermal conductivity by nanostructuring. Our simulation quantitatively identifies the major phonons contributing to the phonon drag, which are spectrally distinct from those carrying heat, and further reveals that although the phonon drag is reduced in heavily doped samples, a significant contribution to Seebeck coefficient still exists. An ideal phonon filter is proposed to enhance zT of silicon at room temperature by a factor of 20 to ∼0.25, and the enhancement can reach 70 times at 100 K. This work opens up a new venue toward better thermoelectrics by harnessing nonequilibrium phonons.
10
Sen, R., N. Vast, and J. Sjakste. "Hot electron relaxation and energy loss rate in silicon: Temperature dependence and main scattering channels." Applied Physics Letters 120, no. 8 (February 21, 2022): 082101. http://dx.doi.org/10.1063/5.0082727.
Анотація:
In this work, we revisit the density functional theory (DFT)-based results for electron–phonon scattering in highly excited silicon. Using the state-of-the-art ab initio methods, we examine the main scattering channels, which contribute to the total electron–phonon scattering rate and the energy loss rate of photoexcited electrons in silicon as well as their temperature dependence. Both temperature dependence and the main scattering channels are shown to strongly differ for the total electron–phonon scattering rate and the energy loss rate of photoexcited electrons. While the total electron–phonon scattering rate increases strongly with temperature, the temperature dependence of the energy loss rate is negligible. Also, while acoustic phonons dominate the total electron–phonon scattering rate at 300 K, the main contribution to the energy loss rate comes from optical modes. In this respect, DFT-based results are found to disagree with conclusions of Fischetti et al. [Appl. Phys. Lett. 114, 222104 (2019)]. We explain the origin of this discrepancy, which is mainly due to differences in the description of the electron–phonon scattering channels associated with transverse phonons.
11
Liu, Xinyu, Quanjie Wang, Renzong Wang, Sheng Wang, and Xiangjun Liu. "Impact of interfacial compositional diffusion on interfacial phonon scattering and transmission in GaN/AlN heterostructure." Journal of Applied Physics 133, no. 9 (March 7, 2023): 095101. http://dx.doi.org/10.1063/5.0134903.
Анотація:
Compositional diffusion at interfaces often occurs during the synthesis of heterostructures, which poses a significant challenge to the reliability and performance of heterostructure-based electronic devices. In this study, the effect of interfacial compositional diffusion on the interfacial phonon transport in GaN/AlN heterostructures has been explored using molecular dynamics and phonon dynamics simulations. It is found the compositional diffusion results in a remarkable reduction in the interfacial thermal conductance (ITC) of the heterostructures, which can be modulated by tuning the compositional diffusion thickness. Phonon wave packet simulations further revealed that the energy transmission coefficient across the interface is strongly phonon frequency-dependent and interfacial morphology-dependent, which is consistent well with the calculated ITC of the structures. The phonon mode conversion and phonon localization are observed at the region of interfaces. Furthermore, it is found that the longitudinal acoustic phonons are more sensitive to the compositional diffusion interface than transverse-acoustic phonons do. However, it is interesting to find that the energy transmission coefficients of transverse-acoustic phonons with a high frequency (above 3.6 THz) across the compositional interface are abnormally higher than those across the sharp interface due to the stronger phonon mode conversion in the compositional diffusion region, which provides additional pathways for energy transmission. Our findings provide a deeper insight into the interfacial phonon scattering and transmission under the coupling effect of interfacial morphology and compositional diffusion.
12
Sun, J. P., H. B. Teng, G. I. Haddad, M. A. Stroscio, and G. J. Iafrate. "lntersubband Relaxation in Step Quantum Well Structures." VLSI Design 8, no. 1-4 (January 1, 1998): 289–93. http://dx.doi.org/10.1155/1998/17823.
Анотація:
Intersubband relaxation due to electron interactions with the localized phonon modes plays an important role for population inversion in quantum well laser structures designed for intersubband lasers operating at mid-infrared to submillimeter wavelengths. In this work, intersubband relaxation rates between subbands in step quantum well structures are evaluated numerically using Fermi's golden rule, in which the localized phonon modes including the asymmetric interface modes, symmetric interface modes, and confined phonon modes and the electron – phonon interaction Hamiltonians are derived based on the macroscopic dielectric continuum model, whereas the electron wave functions are obtained by solving the Schrödinger equation for the heterostructures under investigation. The sum rule for the relationship between the form factors of the various localized phonon modes and the bulk phonon modes is examined and verified for these structures. The intersubband relaxation rates due to electron scattering by the asymmetric interface phonons, symmetric interface phonons, and confined phonons are calculated and compared with the relaxation rates calculated using the bulk phonon modes and the Fröhlich interaction Hamiltonian for step quantum well structures with subband separations of 36 meV and 50meV, corresponding to the bulk longitudinal optical phonon energy and interface phonon energy, respectively. Our results show that for preferential electron relaxation in intersubband laser structures, the effects of the localized phonon modes, especially the interface phonon modes, must be included for optimal design of these structures.
13
Orlov, A. V., and V. I. Zelenskiy. "PHONON SPECTRAL ENERGY DENSITY IN METALSWITH THE CUBIC LATTICE STRUCTURE." Russian Family Doctor, no. 1 (December 15, 2020): 73–78. http://dx.doi.org/10.17816/rfd10681.
Анотація:
This study derives an expression of spectral energy density of acoustic phonons, as well as introducing the basic properties of anharmonic phonons and deriving an expression of their spectral energy density. The description of the vibrations of the atoms of the crystal lattice to this day cannot be considered completely finished, despite the existence of the theory of heat capacity at a constant volume (Debye theory). Debye's theory perfectly explains the law of cubic increase in heat capacity with temperature at low values of the latter. However, at high temperatures, the Debye model seems insufficiently substantiated. In particular, it is not clear for what physical reasons the value of the critical frequency was introduced - the phonon frequency, above which their appearance is impossible. In addition, the spectral energy density of anharmonism phonons is not considered, although this information is extremely important. It is the spectral composition of the anharmonic phonons that is necessary for an objective description of the phonon-phonon interaction in a crystal. In this paper, the principles are stated on the basis of which the spectral energy density of phonons can be calculated. The consideration is carried out for a simple cubic crystal lattice.
14
Orlov, A. V., and V. I. Zelenskiy. "PHONON SPECTRAL ENERGY DENSITY IN METALSWITH THE CUBIC LATTICE STRUCTURE." Russian Family Doctor, no. 1 (December 15, 2020): 73–78. http://dx.doi.org/10.17816/rfd10713.
Анотація:
This study derives an expression of spectral energy density of acoustic phonons, as well as introducing the basic properties of anharmonic phonons and deriving an expression of their spectral energy density. The description of the vibrations of the atoms of the crystal lattice to this day cannot be considered completely finished, despite the existence of the theory of heat capacity at a constant volume (Debye theory). Debye's theory perfectly explains the law of cubic increase in heat capacity with temperature at low values of the latter. However, at high temperatures, the Debye model seems insufficiently substantiated. In particular, it is not clear for what physical reasons the value of the critical frequency was introduced - the phonon frequency, above which their appearance is impossible. In addition, the spectral energy density of anharmonism phonons is not considered, although this information is extremely important. It is the spectral composition of the anharmonic phonons that is necessary for an objective description of the phonon-phonon interaction in a crystal. In this paper, the principles are stated on the basis of which the spectral energy density of phonons can be calculated. The consideration is carried out for a simple cubic crystal lattice.
15
Orlov, A. V., and V. I. Zelenskiy. "PHONON SPECTRAL ENERGY DENSITY IN METALSWITH THE CUBIC LATTICE STRUCTURE." Yugra State University Bulletin 16, no. 1 (December 15, 2020): 73–78. http://dx.doi.org/10.17816/byusu20200173-78.
Анотація:
This study derives an expression of spectral energy density of acoustic phonons, as well as introducing the basic properties of anharmonic phonons and deriving an expression of their spectral energy density. The description of the vibrations of the atoms of the crystal lattice to this day cannot be considered completely finished, despite the existence of the theory of heat capacity at a constant volume (Debye theory). Debye's theory perfectly explains the law of cubic increase in heat capacity with temperature at low values of the latter. However, at high temperatures, the Debye model seems insufficiently substantiated. In particular, it is not clear for what physical reasons the value of the critical frequency was introduced - the phonon frequency, above which their appearance is impossible. In addition, the spectral energy density of anharmonism phonons is not considered, although this information is extremely important. It is the spectral composition of the anharmonic phonons that is necessary for an objective description of the phonon-phonon interaction in a crystal. In this paper, the principles are stated on the basis of which the spectral energy density of phonons can be calculated. The consideration is carried out for a simple cubic crystal lattice.
16
DOLOCAN, ANDREI, VOICU OCTAVIAN DOLOCAN, and VOICU DOLOCAN. "SOME ASPECTS OF THE ELECTRON-BOSON INTERACTION AND OF THE ELECTRON-ELECTRON INTERACTION VIA BOSONS." Modern Physics Letters B 21, no. 01 (January 10, 2007): 25–36. http://dx.doi.org/10.1142/s0217984907012335.
Анотація:
By using a Hamiltonian of interaction between fermions via bosons1 we derive some properties of the electro-phonon and electron-photon interaction and also of the electron-electron interaction. We have obtained that in a degenerate electron gas there is an attraction between two electrons via acoustical phonons. Also, in certain conditions, there may be an attraction between two electrons via longitudinal optical phonons. Although our expressions for the polaron energy in both cases of the acoustical and longitudinal optical phonons are different from that obtained in the standard theory, their magnitudes are the same with these and they are in good agreement with experimental data. The total emission rate of an electron against a phonon system at absolute zero is directly proportional to the electron momentum. Also, an attraction between two electrons may appear via photons.
17
Hasegawa, Takayuki. "Characteristics of Coherent Optical Phonons in a Hexagonal YMnO3 Thin Film." Applied Sciences 9, no. 4 (February 18, 2019): 704. http://dx.doi.org/10.3390/app9040704.
Анотація:
This paper reviews our recent study on a coherent optical phonon in a hexagonal YMnO3 thin film together with related optical studies in hexagonal RMnO3 (R = Y, Lu, Ho) compounds. Coherent phonons have been observed in RMnO3 compounds by pump-probe spectroscopy with subpicosecond laser pulses, whereas the observation of coherent optical phonons was reported only in LuMnO3. Recently, we succeeded in the observation of the coherent optical phonon in a YMnO3 thin film. The generation process of the coherent optical phonon is assigned to a displacive mechanism, which is identical to that in LuMnO3. The coherent optical phonon is observed in the temperature range from 10 K to room temperature, while the oscillation intensity strongly decreases as the temperature increases to the Néel temperature of ~70 K from a lower temperature range. It is interesting that the temperature dependence is largely different from that in LuMnO3. We describe that the result can be qualitatively explained by the property of an isostructural transition around the Néel temperature in RMnO3 compounds. In addition, we briefly discuss ultrafast incoherent responses of excited electronic states from the viewpoint of the excitation photon energy of laser pulses.
18
Matveenko, S. I., and S. Brazovskii. "Theory of pseudogaps in charge density waves in application to photo electron spectroscopy." Journal de Physique IV 12, no. 9 (November 2002): 73. http://dx.doi.org/10.1051/jp4:20020358.
Анотація:
For a one-dimensional electron-phonon system we consider the photon absorption involving electronic excitations within the pseudogap energy range. Within the adiabatic approximation for the electron - phonon interactions these processes are described by ronlinear configurations of an instanton type. We calculate the subgap absorption as it can be observed by means of photo electron or tunneling spectroscopies. In details we consider systems with gapless modes: 1D semiconductors with acoustic phonons and incommensurate charge density waves. We found that below the free particle edge the pseudogap starts with the exponential decrease of transition rates changing to a power law deeply within the pseudogap, near the absolute edge.
19
Frazer, Laszlo, Richard D. Schaller, Kelvin B. Chang, Aleksandr Chernatynskiy, and Kenneth R. Poeppelmeier. "Seeing the invisible plasma with transient phonons in cuprous oxide." Physical Chemistry Chemical Physics 19, no. 2 (2017): 1151–57. http://dx.doi.org/10.1039/c6cp06532e.
20
Nemova, Galina. "Laser Cooling and Trapping of Rare-Earth-Doped Particles." Applied Sciences 12, no. 8 (April 8, 2022): 3777. http://dx.doi.org/10.3390/app12083777.
Анотація:
This review focuses on optical refrigeration with the anti-Stokes fluorescence of rare-earth (RE)-doped low-phonon micro- and nanocrystals. Contrary to bulk samples, where the thermal energy is contained in internal vibrational modes (phonons), the thermal energy of nanoparticles is contained in both the translational motion and internal vibrational (phonons) modes of the sample. Much theoretical and experimental research is currently devoted to the laser cooling of nanoparticles. In the majority of the related work, only the translational energy of the particles has been suppressed. In this review, the latest achievements in hybrid optical refrigeration of RE-doped low-phonon micro- and nanoparticles are presented. Hybrid cooling permits the suppression of not only the translational energy of the RE-doped particles, but also their internal vibrational phonon thermal energy. Laser cooling of nanoparticles is not a simple task. Mie resonances can be used to enhance laser cooling with the anti-Stokes fluorescence of nanoparticles made of low-phonon RE-doped solids. Laser-cooled nanoparticles is a promising tool for fundamental quantum-mechanical studies, nonequilibrium thermodynamics, and precision measurements of forces.
21
Tsybeskov, Leonid. "Nanocrystalline Silicon for Optoelectronic Applications." MRS Bulletin 23, no. 4 (April 1998): 33–38. http://dx.doi.org/10.1557/s0883769400030244.
Анотація:
Light emission in silicon has been intensively investigated since the 1950s when crystalline silicon (c-Si) was recognized as the dominant material in microelectronics. Silicon is an indirect-bandgap semiconductor and momentum conservation requires phonon assistance in radiative electron-hole recombination (Figure 1a, top left). Because phonons carry a momentum and an energy, the typical signature of phonon-assisted recombination is several peaks in the photoluminescence (PL) spectra at low temperature. These PL peaks are called “phonon replicas.” High-purity c-Si PL is caused by free-exciton self-annihilation with the exciton binding energy of ~11 meV. The TO-phonon contribution in conservation processes is most significant, and the main PL peak (~1.1 eV) is shifted from the bandgap value (~1.17 eV) by ~70 meV—that is, the exciton binding energy plus TO-phonon energy (Figure 1a).
22
XING, D. Y., J. YANG, and C. S. TING. "EFFECT OF THE NONEQUILIBRIUM DISTRIBUTION FUNCTION ON THE ENERGY LOSS RATE OF HOT ELECTRONS IN A SEMICONDUCTOR." International Journal of Modern Physics B 09, no. 08 (April 10, 1995): 991–1000. http://dx.doi.org/10.1142/s0217979295000392.
Анотація:
The closed time path Green’s function method is used to derive the nonequilibrium distribution functions of acoustic phonons and excitations of hot electrons, renormalized by the electron-phonon interaction in the random phase approximation, and to calculate the power dissipation of hot electrons. It is shown that the energy loss channel of hot electrons would vanish unless a relaxation rate corresponding to the decay of one acoustic phonon into two or more bare acoustic phonons via the anharmonic interaction is explicitly included in the phonon propagator. The effect due to the anharmonic interaction on the energy loss rate of hot electrons has also been studied.
23
Ohtsu, Motoichi. "Dressed photon technology." Nanophotonics 1, no. 1 (July 1, 2012): 83–97. http://dx.doi.org/10.1515/nanoph-2011-0001.
Анотація:
AbstractThis paper reviews the theoretical picture of dressed photons used to describe the electromagnetic interactions between nanometric particles located in close proximity to each other. The coupling between a dressed photon and multi-mode coherent phonons is also presented, revealing the presence of a novel phonon-assisted process in light-matter interactions. Applications of this novel process to innovative optical devices, fabrication technologies, energy conversion, and hierarchical systems are demonstrated.
24
Capone, M., C. Castellani, and M. Grilli. "Electron-Phonon Interaction in Strongly Correlated Systems." Advances in Condensed Matter Physics 2010 (2010): 1–18. http://dx.doi.org/10.1155/2010/920860.
Анотація:
The Hubbard-Holstein model is a simple model including both electron-phonon interaction and electron-electron correlations. We review a body of theoretical work investigating, the effects of strong correlations on the electron-phonon interaction. We focus on the regime, relevant to high-Tcsuperconductors, in which the electron correlations are dominant. We find that electron-phonon interaction can still have important signatures, even if many anomalies appear, and the overall effect is far from conventional. In particular in the paramagnetic phase the effects of phonons are much reduced in the low-energy properties, while the high-energy physics can still be affected by phonons. Moreover, the electron-phonon interaction can give rise to important effects, like phase separation and charge-ordering, and it assumes a predominance of forward scattering even if the bare interaction is assumed to be local (momentum independent). Antiferromagnetic correlations reduce the screening effects due to electron-electron interactions and revive the electron-phonon effects.
25
Villani, Matteo, and Xavier Oriols. "Can Wigner distribution functions with collisions satisfy complete positivity and energy conservation?" Journal of Computational Electronics 20, no. 6 (November 23, 2021): 2232–44. http://dx.doi.org/10.1007/s10825-021-01798-1.
Анотація:
AbstractTo avoid the computational burden of many-body quantum simulation, the interaction of an electron with a photon (phonon) is typically accounted for by disregarding the explicit simulation of the photon (phonon) degree of freedom and just modeling its effect on the electron dynamics. For quantum models developed from the (reduced) density matrix or its Wigner–Weyl transformation, the modeling of collisions may violate complete positivity (precluding the typical probabilistic interpretation). In this paper, we show that such quantum transport models can also strongly violate the energy conservation in the electron–photon (electron–phonon) interactions. After comparing collisions models to exact results for an electron interacting with a photon, we conclude that there is no fundamental restriction that prevents a collision model developed within the (reduced) density matrix or Wigner formalisms to satisfy simultaneously complete positivity and energy conservation. However, at the practical level, the development of such satisfactory collision model seems very complicated. Collision models with an explicit knowledge of the microscopic state ascribed to each electron seems recommendable (Bohmian conditional wavefunction), since they allow to model collisions of each electron individually in a controlled way satisfying both complete positivity and energy conservation.
26
Dejneka, Matthew J. "Transparent Oxyfluoride Glass Ceramics." MRS Bulletin 23, no. 11 (November 1998): 57–62. http://dx.doi.org/10.1557/s0883769400031018.
Анотація:
Low-phonon energy glasses are desirable hosts for rare-earth (RE) ions because they enable emission from RE energy levels that would otherwise be quenched in high-phonon energy glasses. Such emissions are of interest for fiber amplifiers operating at telecommunications wavelength band s of 1.31, 1.46, and 1.55 μm, and for up-conversion lasers and three-dimensional displays.Phonons are optical-frequency molecular vibrations in a material. If the RE energy level of interest lies only a few phonons in energy above the next lower lying level such as the 1G4 level of Pr3+, which is only 3,000 cm −1 above the 3F4, only three Si—O vibrational phonons (1,100 cm−1) are required to bridge the gap as shown in Figure 1. Thus any electrons excited to the 1G4 level via an external pump source will be deexcited to the 3F4 on down to the 3H4 ground state via phonons, and no radiation of usable light will be produced. This is why emission from the 1G4 level of Pr3+ is absent in silicates and why researchers have gone to great lengths to make low-phonon energy glasses.
27
TAKESHIMA, MASUMI, K. MIZUNO, and ATSUO H. MATSUI. "PHONON SCATTERING OF FRENKEL EXCITONS IN MOLECULAR MICROCRYSTALLITES EMBEDDED IN A MATRIX." International Journal of Modern Physics B 15, no. 28n30 (December 10, 2001): 3973–76. http://dx.doi.org/10.1142/s021797920100913x.
Анотація:
A matrix effect on the exciton-phonon coupling in microcrystallites embedded in a matrix is investigated theoretically. It is shown that a parameter σ defined as the square of the ratio of the phonon bandwidth of a matrix material to that of a microcrystallite material is a crucial one, affecting the exciton-phonon scattering. Phonons flow in the microcrystallite or out of it for either of σ > 1 or σ < 1, respectively; the probability for finding phonons in the microcrystallite increases with increasing σ. Thus the strength of the exciton-phonon coupling in the microcrystallite is influenced by phonons in the matrix. The flowing-in of phonons, which have energies higher than the maximum energy of phonons in the microcrystallite material, is of special importance and results in the broadening of the lines constituting an optical absorption spectrum.
28
Ribeiro, Sofia, Angela Vasanelli, Yanko Todorov, and Carlo Sirtori. "Quantum Theory of Multisubband Plasmon– Phonon Coupling." Photonics 7, no. 1 (February 20, 2020): 19. http://dx.doi.org/10.3390/photonics7010019.
Анотація:
We present a theoretical description of the coupling between longitudinal optical phonons and collective excitations of a two-dimensional electron gas. By diagonalizing the Hamiltonian of the system, including Coulomb electron–electron and Fröhlich interactions, we observe the formation of multisubband polarons, mixed states partially phonon and partially multisubband plasmon, characterized by a coupling energy which is a significant fraction, up to ∼ 40 % , of the phonon energy. We demonstrate that multisubband plasmons and longitudinal optical phonons are in the ultra-strong coupling regime in several III–V and II–VI material systems.
29
Кулеев, И. Г., та И. И. Кулеев. "Влияние фокусировки на взаимное увлечение электронов и фононов и электросопротивление кристаллов калия". Физика твердого тела 64, № 8 (2022): 899. http://dx.doi.org/10.21883/ftt.2022.08.52680.324.
Анотація:
The effect influence of elastic energy anisotropy on the mutual drag of electrons and phonons and the electrical resistance of potassium crystals at low temperatures have investigated. We have analyzed the momentum exchange between the electron and three phonon flows corresponding to three branches of the vibrational spectrum in the hydrodynamic approximation. The actual mechanisms of phonon momentum relaxation have taken into account: scattering at sample boundaries, dislocations, and in the processes of phonon-phonon transfer. It have shown that in the limiting case of strong mutual drag of electrons and phonons, the electrical resistance will be much lower than that given by the Bloch–Grüneisen theory, and the phonon and electron drift velocities are close and they are determined by the total phonon relaxation rate in resistive scattering processes. In the opposite case, when resistive scattering processes dominate for phonons and the phonon system remains in equilibrium, then the electrical resistance follows the Bloch–Grüneisen theory. In this case, the drift velocities of all modes are different and much less than the electron drift velocity.
30
SINGH, NAVINDER. "HOT ELECTRON RELAXATION IN A METAL NANOPARTICLE: ELECTRON SURFACE-PHONON INTERACTION." Modern Physics Letters B 18, no. 24 (October 20, 2004): 1261–65. http://dx.doi.org/10.1142/s0217984904007797.
Анотація:
The relaxation of hot electrons is considered in a metal nanoparticle. When the particle size is of the order of electron mean free path, the main channel of hot electron energy loss is through surface-phonon generation, rather than bulk phonon generation. A calculation for the hot electron relaxation by the generation of surface-phonons is given, assuming that electrons and surface-phonons are described by their equilibrium Fermi and Bose distribution functions. The assumption is valid because the time required to establish equilibrium in the electron gas is much less than the time for achieving equilibrium between the electrons and the surface-phonons. The expressions obtained for low-temperature and high-temperature regimes are inversely proportional to the radius of the particle. This shows that size dependency of electron surface-phonon energy exchange arises from the geometric effect.
31
Kuleyev I. G. and Kuleyev I. I. "The Effect of phonon focusing on the mutual drag of electrons and phonons and the electrical resistance of potassium." Physics of the Solid State 64, no. 8 (2022): 901. http://dx.doi.org/10.21883/pss.2022.08.54601.324.
Анотація:
The effect influence of elastic energy anisotropy on the mutual drag of electrons and phonons and the electrical resistance of potassium crystals at low temperatures have investigated. We have analyzed the momentum exchange between the electron and three phonon flows corresponding to three branches of the vibrational spectrum in the hydrodynamic approximation. The actual mechanisms of phonon momentum relaxation have taken into account: scattering at sample boundaries, dislocations, and in the processes of phonon-phonon transfer. It have shown that in the limiting case of strong mutual drag of electrons and phonons, the electrical resistance will be much lower than that given by the Bloch--Gruneisen theory, and the phonon and electron drift velocities are close and they are determined by the total phonon relaxation rate in resistive scattering processes. In the opposite case, when resistive scattering processes dominate for phonons and the phonon system remains in equilibrium, then the electrical resistance follows the Bloch--Gruneisen theory. In this case, the drift velocities of all modes are different and much less than the electron drift velocity. Keywords: electrical resistance, elastic anisotropy, electron-phonon relaxation.
32
Zhao, Guojun, X. X. Liang, and S. L. Ban. "Binding Energies of Excitons in GaAs/AlAs Quantum Wells Under Pressure." Modern Physics Letters B 17, no. 16 (July 10, 2003): 863–70. http://dx.doi.org/10.1142/s0217984903005329.
Анотація:
The binding energy of an exciton in the GaAs/AlAs quantum well is discussed including the influence of interface optical phonons and bulk longitudinal optical phonons confined in the well under hydrostatic pressure. The dependence of the phonon energies on pressure is considered using a linear interpolation method to obtain the pressure effect on the exciton binding energy by a variational calculation. The result shows that the polaronic effect on the exciton binding energies cannot be neglected and the pressure effect on the exciton-phonon interaction is obvious.
33
Saxena, Kapil, Vivek Kumar, and A. K. Shukla. "Investigation of spatial disorder in graphite by Raman lineshape analysis." Canadian Journal of Physics 90, no. 10 (October 2012): 975–79. http://dx.doi.org/10.1139/p2012-093.
Анотація:
Disorder in graphite is studied as a function of phonon softening of Raman active modes. A comprehensive analysis of disorder is discussed here using the G and D modes of the graphite. Two-dimensional disorder is manifested in the correlation length of the sp2 hybridization in the graphitic plane. It is characterized here by lineshape analysis of Raman activated G and D modes. Phonon softening of the G mode is almost insensitive to disorder. It is more asymmetric on the lower energy side with increasing disorder. Phonon softening and line broadening of the D mode have high sensitivity to disorder in polycrystalline graphite. Electron–phonon coupling is responsible for phonon softening and line broadening of the D mode, which is double-resonant Raman scattering involving disorder, electron, and TO (tansverse optical) phonon. Increasing disorder allows TO phonons of higher wavevector and lower energy during double-resonant Raman scattering.
34
VARSHNEY, DINESH, RAJENDRA JAIN, and NAMITA SINGH. "PHONON DRAG AND CARRIER DIFFUSION CONTRIBUTIONS IN THERMOELECTRIC POWER OF K3C60 FULLERIDES." International Journal of Computational Materials Science and Engineering 01, no. 03 (September 2012): 1250027. http://dx.doi.org/10.1142/s2047684112500273.
Анотація:
The thermoelectric power (S) of K3C60 fullerides is theoretically analyzed. Mott expression within parabolic band approximation is used to reveal the electron diffusive thermoelectric power (Sc diff ) following Fermi energy as electron parameter, Sc diff show linear temperature dependence. S infers a change in slope above transition temperature and become almost linear above 70 K. The phonon drag thermoelectric power (S ph drag ) is computed within relaxation time approximation when thermoelectric power is limited by scattering of phonons from defects, grain boundaries, phonons and electrons as carriers. The S ph drag of K3C60 is anomalous and it is an artifact of strong phonon-electron and phonon scattering mechanism. The thermoelectric power within relaxation time approximation has been taken into account ignoring a possible energy dependence of the scattering rates. Behaviour of S(T) is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions.
35
Lagos, Maureen J., Isobel C. Bicket, S. Shayan Mousavi M., and Gianluigi A. Botton. "Advances in ultrahigh-energy resolution EELS: phonons, infrared plasmons and strongly coupled modes." Microscopy 71, Supplement_1 (February 18, 2022): i174—i199. http://dx.doi.org/10.1093/jmicro/dfab050.
Анотація:
Abstract Nowadays, sub-50 meV atom-wide electron probes are routinely produced for electron energy loss spectroscopy in transmission electron microscopes due to monochromator technology advances. We review how gradual improvements in energy resolution enabled the study of very low-energy excitations such as lattice phonons, molecular vibrations, infrared plasmons and strongly coupled hybrid modes in nanomaterials. Starting with the theoretical framework needed to treat inelastic electron scattering from phonons in solids, we illustrate contributions in detecting optical surface phonons in photonic structures. We discuss phonon mapping capabilities in real and reciprocal space, and the localized phonon response near nano-/atomic-scale structural features. We also survey the progress of aloof spectroscopy in studying vibrations in organic materials and applications in measuring local temperature and photonic density of states in single nanostructures using phonon scattering. We then turn towards studies on infrared plasmons in metals and semiconductors. Spectroscopy analyses now extend towards probing extremely complex broadband platforms, the effects of defects and nanogaps, and some far-reaching investigations towards uncovering plasmon lifetime and 3D photonic density of states. In doped semiconductors, we review research on the use of the electron probe to correlate local doping concentration and atomic-scale defects with the plasmonic response. Finally, we discuss advances in studying strong coupling phenomena in plasmon–exciton and plasmon–phonon systems. Overall, the wealth of information gained extends our knowledge about nanomaterial properties and elementary excitations, illustrating the powerful capabilities of high-energy resolution scanning transmission electron microscopy–electron energy loss spectrometry.
36
Minárik, Stanislav. "Quantization of Energy in 1D Model of Crystal Lattice with Local Perturbations Induced by Ion-Beam Impact." Research Papers Faculty of Materials Science and Technology Slovak University of Technology 23, s1 (August 1, 2015): 71–78. http://dx.doi.org/10.1515/rput-2015-0029.
Анотація:
Abstract In this paper, we propose theoretical basis for investigation of dynamics of acoustic phonons in a thin layers containing nano-scale structural inhomogeneities. One-dimensional (1D) model of a crystal lattice was considered to reveal specific features of the processes arising in such system of phonons in equilibrium state. Standard quantization of energy of 1D ionic chain vibrating by acoustic frequencies was carried out while the presence of foreign ions in this chain was taken into account. Since only two dimensions are dominant in thin layers, only longitudinal vibrations of the chain in the plane of the layer were considered. Results showed that foreign ions affect the energy quantization. Phonon-phonon interaction between two phonon`s modes can be expected if the mass of foreign ions implanted by ion-beam differs from the mass of ions in the initial layer. We believe that the obtained results will help to understand the character of phonon systems in nanostructured thin layers prepared by ion-bem technology, and will allow better explain some thermal and electrical phenomena associated with lattice dynamics in such layers.
37
Vinh, Pham Tuan, Le Dinh, and Luong Van Tung. "OPTICALLY DETECTED ELECTROPHONON RESONANCE AND LINEWIDTHS IN TRIANGULAR QUANTUM WELLS." Hue University Journal of Science: Natural Science 127, no. 1A (August 6, 2018): 119. http://dx.doi.org/10.26459/hueuni-jns.v127i1a.4668.
Анотація:
<p>In the present paper, we study the linear optical absorption power in triangular quantum wells (QW), subjected to a laser field when electrons are scattered with longitudinal optical phonons (LO phonons). The analytic expressions are obtained for optical absorption power via electron-LO phonon scattering . The linear optically detected electrophonon resonance (ODEPR) effect in a specific GaAs/AlAs quantum well with triangular potential is investigated. Conditions for the ODEPR are determined based on the energy conservation law. From the curves expressing the dependence of the absorption power on photon energy we find the ODEPR-linewidths as profiles of the curves. Computational results show that the ODEPR-linewidths increase with temperature and decrease with electric field.</p>
38
Li, Zheng, Hailong Wang, Li Chen, Sha Chen, and Qian Gong. "The electron-longitudinal optical phonon scattering rate in GaInAsP/InP stepped quantum well." International Journal of Modern Physics B 30, no. 26 (October 12, 2016): 1650196. http://dx.doi.org/10.1142/s0217979216501964.
Анотація:
Within the framework of effective mass approximation, the scattering rate via longitudinal optical (LO) phonon emission for an electron and the mean scattering rate via LO phonons emission for electrons initially in the first excited sub-band and finally in the ground sub-band in [Formula: see text] stepped quantum well (QW) is calculated adopting the shooting method and Fermi’s golden rule. The results show that the scattering rate and the mean scattering rate are highly dependent on alloy compositions, well width, initial electron energy, electron temperature and sub-band separation [Formula: see text] between the ground sub-band and the first excited sub-band. When [Formula: see text] is larger than the LO phonon energy, the scattering rate and the mean scattering rate increases with increasing Ga composition, decreasing As composition and increasing well width. However, when [Formula: see text] is smaller than the LO phonon energy, its change tendency is contrary. The scattering rate increases with decreasing initial electron energy if the separation between the initial electron energy and the ground state energy [Formula: see text] is not smaller than the LO phonon energy. The scattering rate and the mean scattering rate increases with rising electron temperature. The mean scattering rate reaches the maximum value when [Formula: see text] is equal to the LO phonon energy. The interruption in the scattering rate happens when the separation between the initial electron energy and [Formula: see text] is smaller than the LO phonon energy. The rapid decrease of the mean scattering rate happens when [Formula: see text] is smaller than the LO phonon energy if [Formula: see text] continues decreasing. In addition, both the scattering rate and the mean scattering rate show little change with different stepped layer widths.
39
Mao, Yudong, Shouyu Liu, Jiying Liu, Mingzhi Yu, Xinwei Li, Moon Keun Kim, and Kaimin Yang. "Phonon Transport Characteristics of Nano-Silicon Thin Films Irradiated by Ultrafast Laser under Dispersion Relation." Buildings 14, no. 1 (January 13, 2024): 210. http://dx.doi.org/10.3390/buildings14010210.
Анотація:
The gray model simplifies calculations by ignoring phonon polarization, but sacrifices a certain level of computational accuracy. In effect, the frequency and wavevector of phonons form complex polarization patterns, which means their propagation modes and vibrational directions have different influences. Therefore, based on the phonon dispersion relations in silicon, the lattice Boltzmann method is used to analyze the phonon transport characteristics in nano-silicon films under ultrafast laser excitation. The results show that the total energy density distribution obtained by superimposing acoustic and optical branches exhibits multiple wave-like behaviors. Among them, the acoustic branch has excellent transfer capability, dominating the rate at which the total energy density reaches a steady state distribution, while the optical branch has stronger heat capacity characteristics, with a greater impact on the peak value of the total energy density. When the heat transfer approaches a steady state, the longitudinal optical branch surprisingly contributes up to 52.73%. This indicates that the often-neglected optical phonons should also receive sufficient attention. Additionally, compared to the results of the gray model, it is found that the dispersion model is preferred when more attention is paid to the propagation characteristics during phonon transport.
40
Sahu, Sivabrata, and G. C. Rout. "A theoretical model study on interplay between Coulomb potential and lattice energy in graphene-on-substrate." International Journal of Computational Materials Science and Engineering 06, no. 02 (March 29, 2017): 1750011. http://dx.doi.org/10.1142/s2047684117500117.
Анотація:
The graphene-on-substrates breaks the sub-lattice symmetry leading to the opening of a small gap. The small band gaps can be enhanced by electron–phonon interactions by keeping strongly polarized superstrate on graphene. To describe the band gap opening in graphene, we propose a tight-binding model Hamiltonian taking into account of third-nearest-neighbor electron-hoppings. We introduce repulsive Coulomb interaction at two sub-lattices of graphene. Further, we consider phonon coupling to the electron densities centered at two sub-lattices in the presence of phonon vibration with a single frequency. For high frequency phonons, the present interaction represents the Holstein interaction. Applying Lang–Firsov canonical transformation in the high phonon-frequency limit, we calculate the modified Coulomb interaction and the effective hopping integral which are functions of electron–phonon coupling, phonon-frequency and nearest-neighbor electron-hopping integral. The electron Green’s functions are calculated by Zubarevs technique. The electron occupancies at two sub-lattices for up and down spins are calculated and computed self-consistently. Finally, we calculate the modulated substrate induced gap of graphene-on-substrate, which is computed numerically for [Formula: see text] grid points for electron momentum. We have studied the interplay of Coulomb interaction, electron–phonon interaction in high phonon-frequency limit. The maximum band gap achieved due to the interplay is nearly 67% more than the substrate induced gap. To achieve this condition, one requires low Coulomb energy for low frequency phonon, while one needs high Coulomb interaction and high electron–phonon interaction of a given lattice vibration frequency. For given electron–phonon interaction and phonon-frequency, the modified gap is enhanced throughout the temperature range with increase of Coulomb interaction.
41
Sato, M., Y. Takahara, M. Matsumoto, N. Kajinami, M. Hanaoka, and M. Iwakawa. "Thermal control of thin films with nano structure." Journal of Physics: Conference Series 2766, no. 1 (May 1, 2024): 012206. http://dx.doi.org/10.1088/1742-6596/2766/1/012206.
Анотація:
Abstract Thermoelectric energy conversions have been attracting much attention, which directly generate electric energy from thermal one by utilizing the Seebeck effect. Among various efforts to improve the conversion efficiency, control of phonon propagation with nano-scale structures has been popular, which utilize phonon scatterings on structural interfaces. The concept is based on the difference of mean free path (MFP) between phonons and electrons (charge carriers). In typical cases with silicon-base devices, MFP of phonons is in an order of 100 nm while that of electrons is 1-10 nm. Thus structures of 10-100 nm size are expected to be effective for suppressing the phonon heat transfer without much reducing the electric transport, leading to conversion efficiency improvement. We have developed a numerical scheme to investigate phonon transport based on the Boltzmann transport equation (BTE) for time development of the phonon distribution function. To treat various shapes of nano-scale structures, we have newly introduced a VOF (volume of fluid) like scheme. In the presentation, we will show results of several test systems of nano-structured Si thin films, with evaluation of effective electric conductivity, to discuss how much nano-scale structures improve the conversion efficiency.
42
Zhang, Jia, Rui Qin, Wenjun Zhu, and Jan Vorberger. "Energy Relaxation and Electron–Phonon Coupling in Laser-Excited Metals." Materials 15, no. 5 (March 3, 2022): 1902. http://dx.doi.org/10.3390/ma15051902.
Анотація:
The rate of energy transfer between electrons and phonons is investigated by a first-principles framework for electron temperatures up to Te = 50,000 K while considering the lattice at ground state. Two typical but differently complex metals are investigated: aluminum and copper. In order to reasonably take the electronic excitation effect into account, we adopt finite temperature density functional theory and linear response to determine the electron temperature-dependent Eliashberg function and electron density of states. Of the three branch-dependent electron–phonon coupling strengths, the longitudinal acoustic mode plays a dominant role in the electron–phonon coupling for aluminum for all temperatures considered here, but for copper it only dominates above an electron temperature of Te = 40,000 K. The second moment of the Eliashberg function and the electron phonon coupling constant at room temperature Te=315 K show good agreement with other results. For increasing electron temperatures, we show the limits of the T=0 approximation for the Eliashberg function. Our present work provides a rich perspective on the phonon dynamics and this will help to improve insight into the underlying mechanism of energy flow in ultra-fast laser–metal interaction.
43
Escobar, Rodrigo, Brian Smith, and Cristina Amon. "Lattice Boltzmann Modeling of Subcontinuum Energy Transport in Crystalline and Amorphous Microelectronic Devices." Journal of Electronic Packaging 128, no. 2 (January 19, 2006): 115–24. http://dx.doi.org/10.1115/1.2188951.
Анотація:
Numerical simulations of time-dependent energy transport in semiconductor thin films are performed using the lattice Boltzmann method applied to phonon transport. The discrete lattice Boltzmann method is derived from the continuous Boltzmann transport equation assuming first gray dispersion and then nonlinear, frequency-dependent phonon dispersion for acoustic and optical phonons. Results indicate that a transition from diffusive to ballistic energy transport is found as the characteristic length of the system becomes comparable to the phonon mean free path. The methodology is used in representative microelectronics applications covering both crystalline and amorphous materials including silicon thin films and nanoporous silica dielectrics. Size-dependent thermal conductivity values are also computed based on steady-state temperature distributions obtained from the numerical models. For each case, reducing feature size into the subcontinuum regime decreases the thermal conductivity when compared to bulk values. Overall, simulations that consider phonon dispersion yield results more consistent with experimental correlations.
44
Khvesyuk, V. I., W. Qiao, and A. A. Barinov. "Kinetics of Phonon Interaction Taken into Account in Determining Thermal Conductivity of Silicon." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 3 (102) (June 2022): 57–68. http://dx.doi.org/10.18698/1812-3368-2022-3-57-68.
Анотація:
The thorough study of the heat carriers --- quasiparticles --- phonons interaction resulted in a pioneering method for calculating the thermal conductivity of nonmetallic solids. As the interactions of phonons are much more complicated than those of usual atoms and molecules, it is necessary to take into account the presence of two types of phonons with different properties; the decay of one phonon into two or the fusion of two phonons into one as a result of interaction; the presence of two types of interaction of phonons, one of which is elastic, the other is inelastic (moreover, the type of interaction results from solving the energy and quasi-momentum conservation equations). The existing methods for determining thermal conductivity, which typically involve solving the Boltzmann transport equation, use the iteration method, whose parameter is the average time between successive phonon interactions, and the calculation results provide little information on all types of interactions. In this research, we developed a method of direct Monte Carlo simulation of phonon diffusion with strict account for their interaction owing to the energy and quasi-momentum conservation laws. Calculations of the thermal conductivity coefficient for pure silicon in the temperature range of 100---300 K showed good agreement with the experiment and calculations of other authors, and also made it possible to consider the phonon kinetics in detail
45
Kumar, Vipin. "Relaxation Dynamics of Carriers in Graphene." Advanced Science Letters 24, no. 8 (August 1, 2018): 5666–68. http://dx.doi.org/10.1166/asl.2018.12172.
Анотація:
We study the damping of anomalous Rabi oscillations in monolayer graphene by means of electron–phonon interaction. Our calculations show that the electron–phonon interaction led to the novel incoherent anomalous Rabi oscillations in graphene. Conventional Rabi oscillations occur near resonance show an energy relaxation discussed elsewhere. Anomalous Rabi oscillations display almost zero energy relaxation in the presence of long-wavelength phonons at the Dirac point in the first Brillouin zone. The role of electron–phonon interaction in dephasing of anomalous Rabi oscillations is prominent far away from the Dirac point. There are huge numbers of anomalous Rabi cycles present near the Dirac point.
46
Ali, Haider, and Bekir Sami Yilbas. "Microscale Thermal Energy Transfer Between Thin Films with Vacuum Gap at Interface." Journal of Non-Equilibrium Thermodynamics 44, no. 2 (April 26, 2019): 123–42. http://dx.doi.org/10.1515/jnet-2018-0092.
Анотація:
Abstract Transfer of phonons through a silicon–diamond thin film pair with a nano-size gap at the interface is examined. The thin film pair is thermally disturbed by introducing 301 K at the silicon film left edge while keeping the other edges of the thin films at a low temperature (300 K). The radiative phonon transport equation is solved numerically to quantify the phonon intensity distribution in the combined films. The frequency dependent formulation of phonon transport is incorporated in the transient analysis. The thermal boundary resistance is adopted at the interface in the formulations. The near-field radiative heat transfer is also adopted at the gap interface, as the vacuum gap size falls within the Casimir limit. The predictions of thermal conductivity are validated through the thermocouple data. It is observed that predictions of thermal conductivity are in agreement with the experimental data. The ballistic phonons play a major role in energy transfer through the gap; their contribution is more significant than that of the near-field radiative heat transfer. Enlarging the size of the gap reduces the influence of the ballistic phonons on the energy transfer in the films. Increasing the silicon film thickness alters the energy transfer through the gap; in this case, the equivalent equilibrium temperature difference is increased at the interface.
47
ZHAO, JIJUN, XIAOSHUANG CHEN, FENGQI LIU, and GUANGHOU WANG. "ELECTRON–PHONON INTERACTION AND ELECTRONIC STRUCTURE OF SMALL METAL CLUSTERS." Surface Review and Letters 03, no. 01 (February 1996): 489–92. http://dx.doi.org/10.1142/s0218625x96000887.
Анотація:
The Su–Schrieffer–Heeger (SSH) Hamiltonian has been extended to study the electron–phonon interaction and the electronic structures of the alkali-like metal clusters. The eigen-energy levels of s valence electrons are obtained from a Hückel-like Hamiltonian including the correction of the electron–phonon interaction in the hopping integral, which is proportional to the variable of bond length. The self-consistent equations for electrons and phonons are solved adiabatically through an iteration process. The energy-level structures of an octahedral Cu6 cluster are calculated with variable electron–phonon coupling constant λ to investigate the influence of electron–phonon interaction on the lattice distortion and electronic structures of metal clusters. The size-dependent ionization potential for small Cun clusters are calculated and compared with the experimental results.
48
Sachkov, V. A. "The influence of atoms of second coordination sphere on phonon dispersion of diamond." Omsk Scientific Bulletin, no. 173 (2020): 111–13. http://dx.doi.org/10.25206/1813-8225-2020-173-111-113.
Анотація:
Within the framework of the phenomenological model of twoparticle interaction, the effect of the interaction energy of atoms from the second coordination sphere on the phonon dispersion is considered. This approach makes it possible to vary the growth of the phonon frequency relative to the optical phonon in the center of the Brillun zone. The effects of the contribution to the Raman spectra from longitudinal optical phonons with frequencies higher than their frequency at the center of the Brillouin zone are discussed. The contribution to the frequency of interaction of atoms from the second coordination sphere for some phonons is obtained in an explicit form. The formulas obtained will be useful for calculating the spectra of Raman scattering of light by optical phonons localized in diamond nanocrystals
49
Lakhno, Victor D. "Translation-Invariant Excitons in a Phonon Field." Condensed Matter 6, no. 2 (June 6, 2021): 20. http://dx.doi.org/10.3390/condmat6020020.
Анотація:
Large-radius excitons in polar crystals are considered. It is shown that translation invariant description of excitons interacting with a phonon field leads to a nonzero contribution of phonons into the exciton ground state energy only in the case of weak or intermediate electron-phonon coupling. A conclusion is made that self-trapped excitons cannot exist in the limit of strong coupling. Peculiarities of the absorption and emission spectra of translation invariant excitons in a phonon field are discussed. Conditions when the hydrogen-like exciton model remains valid in the case of electron-phonon interaction are found.
50
Tyunina, M., M. Savinov, and A. Dejneka. "Small-polaron conductivity in perovskite ferroelectric BaTiO3 films." Applied Physics Letters 121, no. 20 (November 14, 2022): 202901. http://dx.doi.org/10.1063/5.0129831.
Анотація:
In ABO3 perovskite oxide ferroelectrics, electrical conductivity ranges from insulator- to superconductor-type and is virtually critical for all applications of these materials. Compared to bulk ceramics and crystals, ferroelectric thin films can enable advanced control of the conductivity. Here, small-polaron hopping conductivity was evidenced and examined in various pulsed-laser-deposited films of ferroelectric BaTiO3 and reference films of SrTiO3. For this, AC conductivity was studied in a broad range of temperatures and frequencies for films sandwiched between the bottom and top electrodes. In the BaTiO3 films, with increasing temperature, a significant increase in activation energy for small-polaron hopping was found and ascribed to strong electron–phonon coupling and complex lattice oscillations therein. Plain relations of the activation energy to microstructure, composition, or phase transitions were lacking, which corroborated the critical role of phonons. Additionally, a phonon-less transport was detected. It was anticipated that owing to strong electron–phonon coupling, rich phonon ensembles, and coexistence of phonon-stimulated and phonon-less processes, the small-polaron conductivity can heavily vary in ferroelectric films that necessitates further studies.