Atomic arrangements, electronic parameters, and electronic structures in modulation-doped Al_xGa_(1-x)As/In_yGa_(1-y)As/Al_xGa_(1-x)As step quantum wells

摘要

Strain effects and electronic parameters of delta-modulation-doped Al_xGa_(1-x)As/In_yGa_(1-y)As/Al_xGa_(1-x)As step quantum wells were investigated by high-resolution transmission electron microscopy (HRTEM) and Shubnikov-de Haas (S-dH) measurements. An atomic crystal structure for the quantum wells was described based on the HRTEM results and the carrier density and the effective mass of the two-dimensional electron gas (2DEG) occupied in the In_yGa_(1-y)As quantum wells were determined from the S-dH data. The electronic parameters in delta-modulation-doped Al_xGa_(1-x)As/In_yGa_(1-y)As/Al_xGa_(1-x)As step quantum wells were compared with those in GaAs/In_yGa_(1-y)As/Al_xGa_(1-x)As step quantum well. The electronic subband structures in the quantum wells were calculated by a self-consistent method. The present results can help to improve the understanding of the microstructural and electronic properties in delta-modulation-doped Al_xGa_(1-x)As/In_yGa_(1-y)As/Al_xGa_(1-x)As step quantum wells.