Silicon-rich SiGe alloys represent a promising platform for the development of large-area single-mode optical waveguides to be integrated in silicon-based optical circuits. It was found that SiGe layers epitaxially grown on Si successfully guide radiation with a 1.55μm wavelength, but, beyond a critical core thickness, their optical properties were strongly affected by the clustering of misfit dislocations at the interface between Si and SiGe, leading to a significant perturbation of the local refractive index. Transmission electron microscopy and micro-Raman spectroscopy, together with finite-element simulations, provide a complete analysis of the impact of dislocations on optical propagation.

Impact of Misfit Dislocations on Wavefront Distortion in Si/SiGe/Si Optical Waveguides. A.Trita, F.Bragheri, I.Cristiani, V.Degiorgio, D.Chrastina, D.Colombo, G.Isella, H.von Känel, F.Gramm, E.Müller, M.Döbeli, E.Bonera, R.Gatti, F.Pezzoli, E.Grilli, M.Guzzi, L.Miglio: Optics Communications, 2009, 282[24], 4716-22