Abstract
Abstract Strain effects in highly lattice-mismatched InxGa1−xAs/Inp modulation-doped coupled double quantum wells were investigated by transmission electron microscopy (TEM) measurements. The high-resolution TEM images showed that the In0.53Ga0.47As/In0.25Ga0.75As, In0.25Ga0.75As/InAs, and InAs/InP heterointerfaces had very sharp interfacial abruptness. The selected-area electron diffraction pattern obtained from the TEM measurements on the InxGa1−xAs/InP double quantum wells showed that the InxGa1−xAs active layers were grown pseudomorphologically on the InP buffer layer in spite of high lattice mismatch among the active layers. Shubnikov–de Haas and Van der Pauw Hall-effect measurements at 1.5 K showed that the mobility of the two-dimensional electron gas existed in the InxGa1−xAs quantum well was relatively high regardless of the existence of the strain between the InxGa1−xAs active layers and the InP potential barriers. The values of the horizontal and the vertical strains of the In0.25Ga0.75As layer are 1.9845×10−2 and −1.858×10−2 Nm−2, respectively, and those of the InAs layer are −3.128×10−2 and 3.3995×10−2 Nm−2, respectively. A possible crystal structure for the InxGa1−xAs/InP double quantum well is presented based on the TEM results. These results can help improve the understanding of the structural properties for potential applications of strained InxGa1−xAs/InP modulation-doped coupled double quantum wells in long-wavelength optoelectronic devices.
Published Version
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