Structural and optical properties of strained In0.2Ga0.8As-GaAs quantum wells

摘要

We report on Molecular Beam Epitaxial growth and properties of strained In$-0.2$/Ga$-0.8$/As-GaAs quantum well (QW) structures suitable for 980 nm lasers. The QW width was maintained at 80 A and the barrier thickness was varied from 50 A to 300 A. The effects of increasing the barrier width on the structural and optical properties of the QW were examined using double crystal x-ray diffraction rocking scans (DCXRD) and photoluminescence measurements. DCXRD rocking scans revealed satellite peaks from the strained layer quantum wells (SLQW). The linewidth of the peaks decreased as the barrier width was increased. Optical measurements indicate significant improvements in the internal luminescence efficiency in the thick barrier structures. We assign the improvements in the luminescence properties to the reduction of non-radiative centers in the thick barrier structures. The sources of the non-radiative centers are ascribed to structural defects that are generated as a result of strain relaxation in the thin barrier structures. A new broad photoluminescence feature at 0.9 eV was also observed and believed to originate in the AlGaAs:Si cladding region. We shall present these results and discuss the implications of increasing the barrier thickness of In$-0.2$/Ga$-0.8$/As-GaAs QW on the performance of 980 nm lasers.