Ge0.2Si0.8/Si Bragg-reflector mirrors for optoelectronic device applications

Abstract

Previous work has shown that III-V semiconductor multilayer films can be designed to serve as Bragg reflector mirrors in optoelectronic devices. In this letter we extend that work to the fabrication of high reflectivity GexSi1−x/Si mirrors. Column IV designs are constrained both by the small refractive index between Si and GexSi1−x alloys and the limitations of strained layer epitaxy that can produce misfit dislocations in thick mirror stacks. Despite these limitations, we report on mirrors with reflectivities of over 50% at 1.5 μm. Furthermore, certain mirrors were overgrown with p-i-n diodes to demonstrate the feasibility of operation in a vertically illuminated, resonant cavity mode.