Molecular beam epitaxy and characterization of InGaAs/AlAs/AlAsSb coupled double quantum wells with extremely thin coupling barriers

InGaAs/AlAs/AlAsSb coupled double quantum wells (CDQWs) with extremely thin AlAs coupling barriers between InGaAs wells were gown by molecular beam epitaxy. The structural quality was examined by the high-resolution x-ray diffraction and the high-energy transmission electron microscopy. It is confirmed that the CDQWs with the 2 monolayer (ML) AlAs coupling barrier was successfully grown. Clear and sharp peaks corresponding to interband transitions were observed in the photoreflectance spectra of CDQWs with 2 and 3 ML of AlAs coupling barrier. The calculated transition energies correspond well with the measured energies. By reducing the AlAs coupling barrier thickness from 3 to 2 ML, the interband transition energy was redshifted toward the communication wavelength of 1.55 mu m as expected. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3280950]