Femtosecond carrier dynamics in GaAs

Abstract

Femtosecond carrier dynamics in GaAs and Al0.3Ga0.7As are investigated using pump probe measurements of transient absorption saturation. Pulses of 35 fs duration are used both to excite carriers and to investigate their subsequent scattering out of their initial optically excited states. A two-component ultrafast relaxation is observed. In GaAs the initial rapid relaxation occurs on a time scale of 10–35 fs. Measurements performed in Al0.3Ga0.7As indicate that this initial process slows significantly to 130–170 fs for increasing band gap.

Ion beam induced surface and interface engineering

“…The measured electron thermalization time is less than 10 −14 s which decreases when the deposited energy increases, was assumed by Izui in the thermal spike model. Then the hot electron are cooled down by sharing their energy with the cold electrons and an electron-atom interaction including a lattice temperature increase as observed in the fs laser induced modifications in metals [271][272][273][274][275][276]. These observations support the statement that the energy deposited during electron excitation is rapidly shared with the lattice even if the electron temperature may be sustained by refilling the electronic holes.…”

Calculations of theA1Phonon Frequency in Photoexcited Tellurium

“…Initially, the electron and hole distributions will be non-thermal but carrier-carrier scattering [5,6,7] will result in a thermal (Fermi-Dirac) distribution of electrons and of the holes in much less than 100 fs, the time-scale of phonon motion. However, electron-hole recombination, resulting in a common chemical potential for electrons and holes, occurs on a time-scale of approximately 1 ns, which is much longer than the phonon period.…”

The study of transient bleaching effect of indirect bandgap semiconductors induced by femtosecond laser

“…So the n l0 could be expressed as (10) where n 0 and n are the concentration of the free electrons in conduction band before and after femtosecond laser's radiation, respectively.…”