Relaxation of electron spin during high-field transport in GaAs bulk

Abstract

Abstract. A semiclassical Monte Carlo approach is adopted to study the multivalley spin depolarization of drifting electrons in a doped n-type GaAs bulk semiconductor, in a wide range of lattice temperature (40 < T L < 300 K) and doping density (10 13 < n < 10 16 cm −3 ). The decay of the initial non-equilibrium spin polarization of the conduction electrons is investigated as a function of the amplitude of the driving static electric field, ranging between 0.1 and 6 kV/cm, by considering the spin dynamics of electrons in both the Γ and the upper valleys of the semiconductor. Doping density considerably affects spin relaxation at low temperature and weak intensity of the driving electric field. At high values of the electric field, the strong spin-orbit coupling of electrons in the L-valleys significantly reduces the average spin polarization lifetime, but, unexpectedly, for field amplitudes greater than 2.5 kV/cm, the spin lifetime increases with the lattice temperature. Our numerical findings are validated by a good agreement with the available experimental results and with calculations recently obtained by a different theoretical approach.

Antilocalization effect on photo-generated carriers in semi-insulating GaAs sample

“…From the carriers mobility one can derive the elastic scattering time, i.e., t = m h m / e, where m h is the hole effective mass (~0.5 × m 0 ). The mean free path can be calculated from l = v F t, where ( ) Thus, for T = 315 K and using the data presented in Table 1 we estimated t so ~ 4.9 × 10 -11 s. This value agrees with the already reported results for Bulk GaAs samples at room temperature 28 and for those obtained for GaAs quantum wells at low temperatures 8 .…”

Noise-induced effects in nonlinear relaxation of condensed matter systems

“…[124]. In our numerical code the spin polarisation vector is taken into account and calculated for each free electron [121,130,131]. All simulations are obtained in a GaAs bulk having a doping concentration n equal to 10 16 cm −3 at a lattice temperature T L = 300 K. In our algorithm all donors are considered ionised and the free electron concentration is set equal to the doping concentration.…”

Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems

“…The electron transport dynamics is simulated by a semiclassical Monte Carlo algorithm, which takes into account all the possible scattering events of the hot electrons in the medium [154,155] and includes the precession equation of the spin polarisation vector for each free carrier [149,156,157]. The Monte Carlo algorithm has been implemented by using a Multiparticle Multivalley FORTRAN Code, following the procedure extensively described in [158].…”