GaAs中带填充效应与带隙重整化效应的竞争

Competition between band filling effect and band-gap renormalization effect in GaAs

采用时间分辨线偏振光抽运-探测光谱研究常温下本征GaAs中载流子弛豫动力学,观察到饱和吸收和吸收增强现象.发现载流子浓度为2×1017cm-3,探测光子能量小于1.549eV时,饱和吸收现象比较明显,反之,有明显的吸收增强现象出现.载流子浓度大于7×1016cm-3的范围内,吸收增强信号随时间增大没有减弱的趋势,反而有继续增强的趋势.理论上,考虑带填充效应和带隙重整化效应的竞争,模拟得到与实验谱线相符合的结果.同时考虑带填充和带隙重整化效应,给出了用于拟合载流子寿命的新的经验公式.

Time-resolved linearly polarized pump-probe spectroscopy is used to investigate carrier relaxation dynamics in instrinsic GaAs.Absorption saturation and absorption enhancement are observed.It is found that the absorption saturation can be observed obviously when the photon energy is smaller than 1.549eV,otherwise,the absorption enhancement can be observed at a carrier density of 2 × 1017 cm-3.When the carrier density is above 7 × 1016 cm-3,the absorption enhancement increases rather than decreases with delay time.The simulation results with consideration of the competition between band filling effect and band-gap renormalization effect are in good agreement with our experimental results.With the band filling effect and band-gap renormalization effect considered,we develop a new analytical model to retrieve the carrier lifetime.