Spectra of circular and linear photogalvanic effect at inter-band excitation in In_(0.15)Ga_(0.85)As/Al_(0.3)Ga _(0.7)As multiple quantum wells

摘要

Spectra of circular photogalvanic effect (CPGE) and linear photogalvanic effect (LPGE) for inter-band transition have been experimentally investigated in In_(0.15)Ga_(0.85)As/Al_(0.3)Ga_(0.7)As multiple quantum wells (QWs) at room temperature. The CPGE and LPGE spectra are quite similar during the spectral region corresponding to the transitions 1e1hh (the first valence subband of heavy hole to the first conduction band) and 1e2hh, which is also similar to that of the photoconductivity. Comparing the photocurrent induced by LPGE and CPGE along [1 1 0] and [11?0] directions, we obtain the anisotropic ratio of the linear photogalvanic tensor χ and circular photogalvanic tensor γ to be ~(χxxz)/ ~(χyyz)=3.6 and ~(γxy)/~(γyx)=1.3 (x∥[110] and y∥[11?0]), which indicate that the symmetry of the structure belongs to C2v point group and the Rashba spin splitting is the dominant mechanism to induce the k-linear spin splitting of the subband in the In_(0.15)Ga_(0.85)As/Al_(0.3)Ga_(0.7)As QWs. The magnitude of the LPGE is nearly at the same order with that of the CPGE for the investigated spectral region at room temperature.