Doping dependence of spin dynamics of drifting electrons in GaAs bulks

TL;DR

This study investigates how impurity density affects electron spin lifetimes and depolarization lengths in n-type GaAs under electric fields, revealing doping-dependent behaviors and temperature effects through Monte Carlo simulations.

Contribution

It provides a detailed analysis of spin dynamics dependence on doping density and electric field in GaAs, highlighting temperature effects and nonmonotonic behaviors.

Findings

Spin lifetime increases with doping density at low temperatures.

Depolarization length shows nonmonotonic behavior at low electric fields.

At room temperature, spin properties are nearly doping independent.

Abstract

We study the effect of the impurity density on lifetimes and relaxation lengths of electron spins in the presence of a static electric field in a n-type GaAs bulk. The transport of electrons and the spin dynamics are simulated by using a semiclassical Monte Carlo approach, which takes into account the intravalley scattering mechanisms of warm electrons in the semiconductor material. Spin relaxation is considered through the D'yakonov-Perel mechanism, which is the dominant mechanism in III-V semiconductors. The evolution of spin polarization is analyzed by computing the lifetimes and depolarization lengths as a function of the doping density in the range 10^{13} - 10^{16} cm^{-3}, for different values of the amplitude of the static electric field (0.1 - 1.0 kV/cm). We find an increase of the electron spin lifetime as a function of the doping density, more evident for lattice temperatures lower than 150 K. Moreover, at very low intensities of the driving field, the spin depolarization length shows a nonmonotonic behaviour with the density. At the room temperature, the spin lifetimes and depolarization lengths are nearly independent on the doping density. The underlying physics is analyzed.