Screening of hot-carrier relaxation in highly photoexcited semiconductors

Using hole screening effect on hole–phonon interaction to estimate hole density in Mg-doped InN

“…This is due to the fact that only carriers which have the same frequency and wave vector of holes could screen the intraband transitions, which means the carriers within the same valley. 15 The interested hole density in Mg-doped InN ranges from 10 18 cm −3 to 10 19 cm −3 , 8 the same order with the expected critical density of heavy-hole screening N c ϳ 1.55 ϫ 10 19 cm −3 . 14,16 Furthermore, we expect the heavy-hole heating time in InN to be ϳ1.0 ps, after calibrating 17 with the reported hole heating time in GaAs ͑ϳ150 fs͒ ͑Ref.…”

“…3͑a͒. For all samples, the observed hole heating time increased with the photoexcited hole density and exhibit the same hole-density-dependent tendency, [13][14][15] indicating that the hole screening effect on the heavy-hole LOphonon interaction delays the hole-thermalization process. To avoid the hole screening effect, the hole heating time in undoped InN under low illumination is measured to be around 1.1 ps, which is consistent with theoretical prediction.…”

Time-resolved absorption studies of the ZnSe/ZnSTe superlattice

“…the piezoelectric and deformation-potential interaction) is the main process for hot-carrier cooling. Although the rapid carrier cooling in the first few picoseconds suggested LO-phonon bottleneck [27,28] or carrier-LOphonon screening [29][30][31] may not be effective. It is possible that the fast decay of the LO-phonon leads to a nonequilibrium built up of the acoustic-phonon population (the LO-phonon lifetime was measured to be 4.5 ps at 20 K [32] and should be considerably smaller at room temperature).…”

Observation of Structural Anisotropy and the Onset of Liquid-like Motion during the Non-thermal Melting of InSb

“…Before discussing the structural dynamics accessed with these measurements, the time scale of electronic equilibration, [13,14] ambipolar diffusion, [15,16] and phonon emission [17,18] must be addressed because these processes will influence the carrier density and non-thermal melting requires excitation of roughly 10% of the valence electrons [1,4,19]. As will be briefly discussed, theoretical and experimental characterization of these processes support the conclusion that the x-ray pulse for time delays up to a few ps probe a fairly uniformly excited sample with an electronic temperature upwards of 10 000 K and a lattice temperature less than the 798 K melting point of InSb.…”

“…This has been calculated using a simple approximation to the InSb conduction band density of states [21]. Cooling of the electronic system will be comparatively slow because the optical phonon emission time for electrons occurs with an average rate of 1-3 ps for the energy range populated at low carrier density and theory indicates that carrier screening at high densities will reduce the emission rate [13,17,18].…”