2.0 μ m wavelength InAs quantum dashes grown on a GaAs substrate using a metamorphic buffer layer

We describe optical and structure characteristics of InAs quantum dashes grown on a GaAs substrate using an AlGaAsSb metamorphic buffer. The metamorphic buffer increases the lattice constant of the growth matrix from 5.653 to 5.869 Å. The increased lattice constant of the growth matrix yields a lattice mismatch with the InAs active region of only 3.2% and accommodates a large In content to access emission wavelengths >2.0 μm. From our comparison with quantum dot structures, we conclude that the elongated quantum dash formation is due to asymmetric surface bonds in the zinc blende crystal structure that control surface migration in low strain conditions.