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We report on a mechanism for ordering of self-assembling InP quantum dots which are prepared by molecular-beam epitaxy on a strained In 0.61 Ga 0.39 P buffer layer on ͑001͒ GaAs. A pronounced alignment of InP nanoscale clusters is observed along the ͗110͘ directions. This phenomenon is attributed to the diffusion of surface adatoms driven by the stress of misfit dislocations confined at the In 0.61 Ga 0.39 P/GaAs interface.

Broad area lasers emitting near 915 nm are fabricated using a 2-step epitaxial growth process, with an intermediate implantation of silicon or oxygen ions. This approach allows for the introduction of buried lateral current confinement layers at moderate cost in terms of process complexity. The effectiveness of this strategy with respect to different implantation conditions is tested, obtaining up to ≈12% reduction of threshold current and ≈15% increase of slope efficiency with respect to standard lasers. Also a significant improvement of the beam qualitywhich is relevant to coupling efficiency-has been obtained in terms of reduction of the lateral beam product parameter, from 3.8 mm×mrad at 5A for standard lasers to 2.2 mm×mrad for implanted and regrown lasers, but at the expense of energy efficiency.

In this study 1.1–1.3 μm wavelength light emitting diode (LED) structures with InxGa1−xAs compositionally graded buffers were grown on GaAs substrates with molecular beam epitaxy and characterized using microstructure and discrete device characterization techniques. The growth temperature and design of the graded buffer greatly affect the luminescence properties of the active device region above the graded buffer. These effects were most prominent in LED structures which incorporated a quantum well in the active device region. In quantum well devices, bright luminescent bands in the 〈110〉 directions are revealed under cathodoluminescence investigation and the number of bands and their intensity depend on grading rate. This study shows that a high threading dislocation density generated at or above the quantum well region has an adverse effect on the I–V characteristics of the diodes, but did not hinder luminescence from the quantum well LEDs.