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

Abstract

In Ga As ∕ Al As ∕ Al As Sb 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 1.55μm as expected.