Strain relaxation and surface migration effects in InGaAlAs and InGaAsP selective-area-grown ridge waveguides

Surface migration of the group-III precursors and strain relaxation at the ridge sidewalls are compared for 2.5 mu m wide waveguides based on InGaAsP and InGaAlAs multiple-quantum-well (MQW) structures. The cross-sectional thickness and strain variations have been measured using synchrotron radiation-based x-ray diffraction with an angular resolution of 2 arc s and a beam size of (0.24x0.35) mu m(2). Indium-rich overgrowth has been observed for the InGaAsP-based waveguides, while InGaAlAs-based waveguides demonstrate thickness uniformity of the MQW active region with a strain relief of 0.4%/mu m at the sidewalls. (c) 2006 American Institute of Physics.