Electron-surface Optical Phonon Interaction Research Articles

Intrinsic surface states with electron–surface optical phonon interaction influence in wurtzite Zn-IV-N2 semiconductors

The electronic intrinsic surface states in wurtzite Zn-IV-N2 (with group-[Formula: see text], Ge and Si) semiconductors were investigated using an intermediate-coupling variational approach considering the electron–surface optical phonon interaction influence. The intrinsic surface state energy distribution and the average penetrating depth of surface state eigen-wave function of the electron have been evaluated numerically by changing the surface potential barrier [Formula: see text] for wurtzite ZnSnN2, ZnGeN2 and ZnSiN2, respectively. The results show that the electronic intrinsic surface state energy increased linearly with increasing surface potential barrier [Formula: see text] for all the calculated materials. The result also indicated that the electronic intrinsic surface state energies variations due to the influence of electron–surface optical phonon interaction are dozens of[Formula: see text]meV. The average penetrating depth of electronic surface state eigen-wave function is independent of [Formula: see text]. Its value is no more than the corresponding material’s lattice constant. The electronic scattering by surface optical phonon should be taken into account in the study of the intrinsic surface state of electrons in the group of Zn-IV-nitrides (with [Formula: see text], Ge and Si) semiconductors, especially for materials having strong electron–phonon interaction and wide band gap.

Manipulating electronic dynamics of 8-Pmmn borophene with surface optical phonons

In this work, the effects of surface optical (SO) phonons on the electronic spectrum of 8-Pmmn phase borophene have been investigated. To describe the analytical model we used a Fröhlich-type Hamiltonian on a borophene system within the continuum limit. Then, by following the analytical model with the Lee–Low–Pines variational approximation method, including two successive unitary transformations, the system Hamiltonian has been diagonalized. Our theoretical analysis indicates that SO absorption of the system strongly depends on the substrate-induced effects of the system. Moreover, it is observed that the polaronic energy gap decreases when increasing the internal distance between the 8-Pmmn borophene and the particular substrate. Also, the energy gap increases with increasing phonon energy (). In addition, the resulting bandgap induced by the electron–SO phonon interaction can be tuned by the associated interaction strengths of the substrate. Furthermore, taking lattice vibrations into account, the surface phonon specific heat of the system has been evaluated as a function of temperature. The specific heat becomes constant at high temperatures, as in the Einstein model. We specifically evaluated the contribution from the lattice vibrations on specific internal distances, z. The increase in the internal distance z causes the peak to shift to lower thermal energy.

Effects of electric field and size on the electron-phonon interaction in a spherical quantum dot with impurity

The effects of electric field and size on the electron-phonon interaction with an on-center impurity in a Zn1−xCdxSe/ZnSe spherical quantum dot are studied, taking into account the interactions with confined, half-space and surface optical phonons. In addition, the interaction between impurity and phonons has also been considered. The results show that the electron-confined, electron-half-space, and electron-surface optical phonon interaction energies are all negative. The electron-confined optical phonon interaction energy is weakened by the electric field, but the electron-half-space and electron-surface optical phonon interaction energies are strengthened by it. In particular, the electron-surface optical phonon interaction depends strongly on the electric field, and it will vanish when the electric field is absent. It is also found that the electron-confined optical phonon interaction and electron-impurity “exchange” interaction energies reach a peak values as the quantum dot radius increases and then gradually decrease, but the electron-half-space optical phonon interaction energy exponentially quickly approaches 0 as the quantum dot radius increases.

Surface polar optical phonon interaction induced many-body effects and hot-electron relaxation in graphene

We theoretically study various aspects of the electron-surface optical phonon interaction effects in graphene on a substrate made of polar materials. We calculate the electron self energy in the presence of the surface phonon-mediated electron-electron interaction focusing on how the linear chiral graphene dispersion is renormalized by the surface phonons. The electron self energy as well as the quasiparticle spectral function in graphene are calculated, taking into account electron-polar optical phonon interaction by using a many-body perturbative formalism. The scattering rate of free electrons due to polar interaction with surface optical phonons in a dielectric substrate is calculated as a function of the electron energy, temperatures, and carrier density. Effects of screening on the self energy and scattering rate are discussed. Our theory provides a comprehensive quantitative (and qualitative) picture for surface phonon interaction induced many-body effects and hot-electron relaxation in Dirac materials.

Effect of electron–phonon interaction on surface states in wurtzite nitride semiconductors under pressure

A variational theory is proposed to study the electronic surface states in semi-infinite wurtzite nitride semiconductors under the hydrostatic pressure. The electronic surface state energy level is calculated, by taking the effects of the electron–Surface–Optical–phonon interaction, structural anisotropy and the hydrostatic pressure into account. The numerical computation has been performed for the electronic surface state energy levels, coupling constants and the average penetrating depths of the electronic surface state wave functions under the hydrostatic pressure for wurtzite GaN, AlN and InN, respectively. The results show that electron–Surface–Optical–phonon interaction lowers the electronic surface state energy levels. It is also found that the electronic surface state energy levels decrease with the hydrostatic pressure in wurtzite GaN and AlN. But for wurtzite InN, the case is contrary. It is shown that the hydrostatic pressure raised the influence of electron–phonon interaction on the electronic surface states obviously. The effect of electron–Surface–Optical–phonon interaction under the hydrostatic pressure on the electronic surface states cannot be neglected, in specially, for materials with strong electron–phonon coupling and wide band gap.

EFFECTS OF CONFINED LO AND SO PHONON MODES ON POLARON IN FREESTANDING CYLINDRICAL QUANTUM WIRE WITH PARABOLIC CONFINEMENT

The electron self-energy and correction to the electron effective mass in a freestanding quantum wire with parabolic confining potential was investigated by the perturbation approach. Both the electron-confined longitudinal optical (LO) phonon and surface optical (SO) phonon interactions were considered. Results shows that, for small wire radius, the contributions of electron–LO phonon interaction to the electron self-energy and the correction to the electron effective mass are relatively small in compare with those of the electron–SO phonon interaction.

Optical phonon modes and electron–phonon interaction in a quantized CdS spherical film

Abstract The confined longitudinal-optical (LO) phonon and surface-optical (SO) phonon modes of a quantized CdS spherical film are discussed within the dielectric continuum (DC) approximation. Two branches of SO phonon modes localized at the inner and outer surface of the film have been investigated. The frequencies of the SO phonons are found to be dispersed and radius dependent for small size systems. When the quantum number l → ∞ , the frequencies of each SO modes converge to the frequency values of the single planar heterostructure. The coupling intension between electron and SO phonons is found to be size-dependent and the electron–SO phonon interaction with different well-width has also been discussed.

Electron–phonon interaction effects on the surface states in wurtzite nitride semiconductors

A variational approach is used to study the surface states of an electron in a semi-infinite wurtzite nitride semiconductor. The surface-state energy of the electron is calculated, by taking the effects of the electron–surface optical phonon interaction and structure anisotropy into account. The numerical computation has been performed for the energies of the electronic surface states as a function of the surface potential V 0 for wurtzite GaN, AlN, and InN, respectively. The results show that the electron–phonon interaction lowers the surface state energy. It is also found that the energies of the electronic surface-state in wurtzite structures are lower than that in the zinc-blende structures by hundreds of meV for the materials calculated. The influence of e–p-interactions on the surface state of electron cannot be neglected.

Effect of electron-phonon interaction on surface states in zinc-blende GaN, AlN, and InN under pressure

A variational approach is used to study the surface states of electrons in a semi-infinite polar semiconductor under hydrostatic pressure. The effective Hamiltonian and the surface-state levels are derived including the effects of electron-optical phonon interaction and pressure. The numerical computation has been performed for the surface-state energies versus pressure for zinc-blende GaN, AlN, and InN. The results show that the effect of electron-optical phonon interaction lowers the surface-state energy. It is also found that the effect of electron-surface optical phonon interaction is much bigger than the effect of electron-half space longitudinal optical phonon interaction for surface-state levels. It indicates that the surface-state energies and the influence of electron-phonon interaction increase with pressure obviously.

Electron-phonon interaction effects on surface states of polar crystals

A variational approach is used to study the surface states of polarons in a semi-infinite polar crystals. The surface-state energy of an electron is calculated, by including the effect of the electron surface-optical phonon interaction. The numerical results for the energies of the surface-states of the polarons in several I-VII II-VI and III-V compounds crystal are obtained and discussed. It is found that the variational results for the surface-state levels are lower than those obtained via the previous near-free-electron approximation perturbation method. The electron-phonon coupling lowers the surface-state energy levels and cannot be neglected, especially for materials with strong electron-phonon-coupling and broad band gaps.

Cyclotron Resonance of a Magnetopolaron in a Quantum Well at Finite Temperatures

Taking into account the interaction of an electron with both bulk longitudinal–optical (BO) and surface–optical (SO) phonons, the cyclotron resonance of a magnetopolaron in a quantum well at finite temperatures is investigated by using the generalized Larsen perturbation–theory method. It is shown that the absorption and emission resonances must be considered at the same time at finite temperatures. The results also show that the electron–SO phonon interaction plays an important role as well as the electron–BO phonon interaction, especially when the quantum well width is getting thinner. For an experimentally interesting sandwich structure, the splitting of the cyclotron resonance spectrum and the temperature dependence of two splitting cyclotron resonance mass of the magnetopolaron in the resonant magnetic field region have been studied.

Theory of surface polarons

We investigate the possibility that an electron may be trapped at the surface of an ionic crystal by the electron-surface optical phonon interaction. For a model Hamiltonian used earlier in a discussion of the inelastic scattering of low energy electrons by surface optical phonons, we find that for all values of the polaron coupling constant α, this trapping does occur. We refer to these surface states as surface polaron states. By the use of a variational procedure, we calculate the surface polaron binding energy and effective mass as a function of α. The present treatment does not include the coupling of the electron to bulk LO phonons.