In this work, we report on In<sub>x</sub>Ga<sub>1-x</sub>As<sub>1-y</sub>Sb<sub>y</sub>/GaSb structures, where the indium mole fraction (x) varies from x=0 to x<0.50. Although there has been considerable effort to exploit high-indium content In<sub>x</sub>Ga<sub>1-x</sub>As<sub>1-y</sub>Sb<sub>y</sub> for longer wavelength applications, high misfit dislocation densities are inevitable and the miscibility gap remains a formidable barrier. In addition to atomically smooth structures, we observed three-dimensional networks of quantum dashes and other results reveal a self-organized composition modulation. Some physical features of the quantum dashes include near one-micron lengths, 90° flip in orientation, and uniformity across a 20 x 20 μm area. We also observe network formation up to a film thickness of 10-nm.
In this work, we perform spectroscopic studies of AlGaAs/InGaAs quantum cascade laser structures that demonstrate
frequency mixing using strain-compensated active regions. Using a three-quantum well design based on diagonal
transitions, we incorporate strain in the active region using single and double well configurations on various surface
planes (100) and (111). We observe the influence of piezoelectric properties in molecular beam epitaxy grown
structures, where the addition of indium in the GaAs matrix increases the band bending in between injector regions and
demonstrates a strong dependence on process conditions that include sample preparation, deposition rates, mole fraction,
and enhanced surface diffusion lengths. We produced mid-infrared structures under identical deposition conditions that
differentiate the role of indium(strain) in intracavity frequency mixing and show evidence that this design can potentially
be implemented using other material systems.