Effect of Quasi-Fermi Level on the Degree of Electron Spin Polarization in GaAs

With spin-polarized-dependent band gap renormalization effect taken into account, the energy-dependent evolution of electron spin polarization in GaAs is calculated at room temperature and at a low temperature of 10 K. We consider the exciting light with right-handed circular polarization, and the calculation results show that the degree of electron spin polarization is dependent strongly on the quasi-Fermi levels of |1/2\rangle and |-1/2\rangle spin conduction bands. At room temperature, the degree of electron spin polarization decreases sharply from 1 near the bottom of the conduction band, and then increases to a stable value above the quasi-Fermi level of the |-1/2\rangle band. The greater the quasi-Fermi level is, the higher the degree of electron spin polarization with excessive energy above the quasi-Fermi level of the |-1/2\rangle band can be achieved. At low temperature, the degree of electron spin polarization decreases from 1 sharply near the bottom of the conduction band, and then increases with the excessive energy, and in particular, up to a maximum of 1 above the quasi-Fermi level of the |1/2\rangle band.