GaAs导带中电子自旋极化的能量演化

考虑自旋极化依赖的带隙重整化效应,分别计算了常温与10 K的低温下GaAs导带中光注入电子自旋极化度的能量演化。计算过程中假设右旋圆偏振光激发,载流子浓度为2×1017 cm-3。发现常温下电子初始自旋极化度随过超能量的增大而增大,并非为通常认为的0.5。而在低温下,导带底附近电子初始自旋极化度几乎为0,电子初始自旋极化度也随过超能量的增大而增大,高能级上可以获得100%的电子初始自旋极化度。

Energy-dependent evolution of electron spin polarization in conduction band of GaAs

With spin-polarized-dependent band-gap renormalization effect taken into account, the energy-dependent evolution of photoexcited electron spin polarization is calculated at room temperature and low temperature. We consider the exciting light to have right-handed circular polarization, and the carrier density is 2?017cm-3. At room temperature, the initial degree of spin polarization is less than 0.5, and increase with increasing carrier densities. At low temperature, the initial degree of spin polarization is almost 0 near the bottom of the conduction band, the initial degree of spin polarization also increase with increasing carrier densities, and in particular, up to a maximum of 100% in larger excess-energy states.