Energy and Momentum Loss Rates for Hot Electrons in Silicon

Abstract

Using of time-dependent perturbation and deformation potential theories for electronphonon interaction, the rate of change of crystal momentum and energy of electron along the field direction has been estimated in silicon. It is found that the loss rate of crystal momentum of the electron along field direction, due to acoustic phonon collisions is greater than that due to optical phonon collisions, whereas the rate of loss of energy of electrons due to optical phonon interactions is greater than that due to acoustic phonon collisions.The dominant acoustic phonon contribution to the loss rate of the crystal momentum of the electron along field direction is confirmed by the observed and estimated temperature dependence of the drift velocity of electrons in silicon for high electric fields.

Photoexcited electron dynamics and energy loss rate in silicon: temperature dependence and main scattering channels

“…12, the rate of energy transfer from electrons to phonons in silicon (referred to as the energy relaxation rate in Refs. 3,6,12, and energy loss rate in other works 14 ) has been measured by two-photon photoemission experiment over a large range of photoexcited electron energies, at 300 K, and found in good agreement with DFT-based calculations. 12 Here, we examine, using methods based on density functional theory (DFT), the temperature dependence and the main scattering channels of the energy loss rate of the photoexcited electrons in silicon, due to the electron-phonon scattering, and compare them to those of the total scattering rate.…”

“…Provided that often, timeresolved spectroscopy provides only the insight into the energy transfer, it is important to keep in mind that some properties, such as temperature dependence and main scattering scattering channels, might not be the same for the total scattering rate and for the energy transfer rate, even if both rates are determined by the electron-phonon scattering. 3,14,15 jelena.sjakste@polytechnique.edu…”

Engineered ‘Nanomaterials by design’ theoretical studies experimental validations current and future prospects

“…Because of strong coupling between an electron and the polymeric chain, it causes significant perturbation leading to formation of a mobile species that may be charged or neutral having high field mobility around 0.1 cm 2 /Vs [86]. In an organic molecule, in general, the strong coupling between the electronic structure, molecular geometry, and the chemical structureall put together determine the bond formation and therefore, for including the influence of such quasi particles in the overall charge carrier transport in organic molecules, the concept of "polaron" was introduced in 1980s for understanding the electronic and optical properties [87][88][89][90]. Further, it is also expected that adding an excess electron into a conjugated polymer chain would add a new band-gap state forming singly charged polaron.…”

“…In a conventional semiconductor with rigid lattice, it is well-known that the transport properties of electrons and holes are governed by their interactions with lattice phonons as the major cause of momentum and energy relaxations resulting in temperature dependent mobility of the charge carriers [1,90]. However, the situations differ in case of ionic or highly polar crystalline materials like II-VI semiconductors, alkali halides, and oxides, where the charge carriers cause significant distortions in the surrounding regions due to attraction/repulsion of the surrounding ions.…”

Impurity and Temperature Dependence of Saturated Drift Velocity in Silicon

“…The drift velocity of electrons in silicon in the hot electron range approaches a constant value which varies with the temperature of the lattice (1). It has been shown theoretically that the temperature dependence of drift velocity comes about from the momentum loss due to acoustic phonons (2,3 ) . The theoretical drift velocity agrees well with the experimental results above room temperature.…”