Photogalvanic effects for interband transition in p-Si_(0.5)Ge_(0.5)/Si multiple quantum wells

摘要

Circular photogalvanic effect (CPGE) and linear photogalvanic effect for interband transition have been observed simultaneously in Si_(0.5)Ge_(0.5)/Si multiple quantum wells. The signature of the CPGE is evidenced by the change of its sign upon reversing the radiation helicity. It is found that the observed CPGE photocurrent is an order of magnitude greater than that obtained for intersubband transition. The dependences of the CPGE on the angle of incidence and the excitation intensities can be well interpreted based on its characteristics. The large signal of spin generation observed here at room temperature should be very useful for the realization of practical application of spintronics.