We report time resolved measurements of spin and carrier relaxation in InAs films with carrier densities of 1.3 1016 and 1.6 1016 cm−3 grown on 001 and 111 GaAs, respectively. We used standard pump-probe and magneto-optical Kerr effect spectroscopy at different excitation wavelengths, power densities, and temperatures. We observed sensitivity of carrier and spin relaxation time to the photoindu...

The ultrafast relaxation and recombination dynamics of photogenerated electrons and holes in epitaxial graphene are studied using optical-pump terahertz-probe spectroscopy. The conductivity in graphene at terahertz frequencies depends on the carrier concentration as well as the carrier distribution in energy. Time-resolved studies of the conductivity can therefore be used to probe the dynamics ...

Recent pump-probe experiments performed on graphene in a perpendicular magnetic field have revealed carrier relaxation times ranging from picoseconds to nanoseconds depending on the quality of the sample. To explain this surprising behavior, we propose a novel symmetry-breaking defect-assisted relaxation channel. This enables scattering of electrons with single out-of-plane phonons, which drast...

We have studied carrier dynamics in In(2)O(3) nanocrystals grown on a quartz substrate using chemical vapor deposition. Transient differential absorption measurements have been employed to investigate the relaxation dynamics of photo-generated carriers in In(2)O(3) nanocrystals. Intensity measurements reveal that Auger recombination plays a crucial role in the carrier dynamics for the carrier d...

Hot carrier-induced spin dynamics is analyzed in epitaxial Au/Fe/MgO(001) by a time domain approach. We excite a spin current pulse in Fe by 35 fs laser pulses. The transient spin polarization, which is probed at the Au surface by optical second harmonic generation, changes its sign after a few hundred femtoseconds. This is explained by a competition of ballistic and diffusive propagation consi...

Carrier relaxation processes have been investigated in GaAs/AlxGa1−xAs v-groove quantum wires (QWRs) with a large subband separation sDE.46 meVd. Signatures of inhibited carrier relaxation mechanisms are seen in temperature-dependent photoluminescence (PL) and photoluminescence-excitation measurements; we observe strong emission from the first excited state of the QWR below ,50 K. This is attri...

Temperature and carrier density-dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs) with different structural symmetries have been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for the symmetrically designed GaAs QW comparing with the asymmetrical one, indicating the strong influence of Rashba spin-orbit coupling on spin r...

We present an empirical model for the electron energy relaxation time. It is based on Monte-Carlo simulation results, and is applicable to all relevant diamond and zinc-blende structure semiconductors. The energy relaxation times are expressed as a function of the carrier and lattice temperatures and, in the case of semiconductor alloys, the material composition. keywords: energy relaxation tim...

We have examined the kinetics of carrier relaxation in three-dimensionally confined GaAs/AlGaAs layers obtained by growth on prepatterned GaAs~001! with time-resolved cathodoluminescence ~CL!. Time-delayed CL spectra at 87 K reveal that ~i! relaxation of hot carriers into the largest 3D confined regions occurs on a time scale of a few hundred ps during the onset of luminescence, and ~ii! the lu...