Institute of Micro/Nano Devices and Solar Cells, School of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, People's Republic of China.
Nanoscale Res Lett. 2014 Mar 19;9(1):130. doi: 10.1186/1556-276X-9-130.
: Spin photocurrent spectra induced by Rashba- and Dresselhaus-type circular photogalvanic effect (CPGE) at inter-band excitation have been experimentally investigated in InGaAs/GaAs/AlGaAs step quantum wells (QWs) at room temperature. The Rashba- and Dresselhaus-induced CPGE spectra are quite similar with each other during the spectral region corresponding to the transition of the excitonic state 1H1E (the first valence subband of heavy hole to the first conduction subband of electrons). The ratio of Rashba- and Dresselhaus-induced CPGE current for the transition 1H1E is estimated to be 8.8±0.1, much larger than that obtained in symmetric QWs (4.95). Compared to symmetric QWs, the reduced well width enhances the Dresselhaus-type spin splitting, but the Rashba-type spin splitting increases more rapidly in the step QWs. Since the degree of the segregation effect of indium atoms and the intensity of build-in field in the step QWs are comparable to those in symmetric QWs, as proved by reflectance difference and photoreflectance spectra, respectively, the larger Rashba-type spin splitting is mainly induced by the additional interface introduced by step structures.
室温下，在 InGaAs/GaAs/AlGaAs 阶跃量子阱（QW）中，实验研究了在带间激发下由 Rashba 和 Dresselhaus 型圆光电流（CPGE）引起的自旋光电流谱。在对应于激子态 1H1E（重空穴的第一价带子到电子的第一导带子）跃迁的光谱区域内，Rashba 和 Dresselhaus 引起的 CPGE 光谱非常相似。对于跃迁 1H1E，Rashba 和 Dresselhaus 引起的 CPGE 电流的比值估计为 8.8±0.1，远大于对称 QW（4.95）中的比值。与对称 QW 相比，减小的阱宽增强了 Dresselhaus 型自旋分裂，但在阶跃 QW 中，Rashba 型自旋分裂增加得更快。正如分别由反射率差和光反射谱证明的那样，阶跃 QW 中铟原子的分凝效应程度和内置场的强度与对称 QW 相当，因此较大的 Rashba 型自旋分裂主要是由阶跃结构引入的附加界面引起的。
