Hot Electrons in Semiconductors Subjected to Quantizing Magnetic Fields

Fundamental mechanisms of nanosecond-laser-ablation enhancement by an axial magnetic field

“…However, the magnetic field can appreciably reduce the rates of electron-electron and electron-phonon collisions [49,50] even at moderate values of the magnetic field. The most significant reduction is for the rate of electronelectron collisions responsible for the fastest de-phasing of magnetic-field-driven cycling [50]. Among various electron-phonon collisions, electron collisions with polar phonons are the fastest [42].…”

“…Among various electron-phonon collisions, electron collisions with polar phonons are the fastest [42]. Their rate can experience a few-fold reduction by the magnetic field [49,50]. Those effects are highly supportive for extending of the partial cyclotron motion of the electrons and holes towards a full cyclotron cycle.…”

“…This qualitative conclusion perfectly correlates with the remarkable similarity of the ablation features on silicon and steel, and the specific behavior of the titanium alloy. The specific at the liquid-solid interfaces are highly favorable for enhanced thermomagnetic effects that result from a modification of thermal conductivity by the magnetic field [49,50,[54][55][56]. In general case, thermal conductivity contains contributions from free carriers and phonons [42], but the free-carrier contribution is the only one affected by the magnetic field [49,50,55].…”

“…The specific at the liquid-solid interfaces are highly favorable for enhanced thermomagnetic effects that result from a modification of thermal conductivity by the magnetic field [49,50,[54][55][56]. In general case, thermal conductivity contains contributions from free carriers and phonons [42], but the free-carrier contribution is the only one affected by the magnetic field [49,50,55]. In metals, the free-carrier thermal conductivity dominates [44], and the perturbation theory of the thermomagnetic effects [55][56][57] delivers the following linear scaling with the magnetic field:…”

“…Thermophysical properties of silicon [ 52], stainless steel 316L [53], and titanium alloy Ti6Al4V [54]. In silicon prior to laser action, the effect of magnetic field on thermal conductivity is negligible because the phonon mechanism of heat transfer dominates at low density of free carriers [42,49,50,55]. However, the laser-induced generation of the free electrons due to the one-photon inter-band transitions rapidly increases the free-carrier density at the very beginning of a laser pulse.…”