Surface Encapsulation for Low-Loss Silicon Photonics

Abstract

Encapsulation layers are explored for passivating the surfaces of silicon to reduce optical absorption in the 1500-nm wavelength band. Surface-sensitive test structures consisting of microdisk resonators are fabricated for this purpose. Based on previous work in silicon photovoltaics, coatings of SiNx and SiO2 are applied under varying deposition and annealing conditions. A short dry thermal oxidation followed by a long high-temperature N2 anneal is found to be most effective at long-term encapsulation and reduction of interface absorption. Minimization of the optical loss is attributed to simultaneous reduction in sub-bandgap silicon surface states and hydrogen in the capping material.

4 pages, 3 figures

References in corpus (2)

• An optical fiber-taper probe for wafer-scale microphotonic device characterization
• Measuring the role of surface chemistry in silicon microphotonics

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• Multimode optomechanics with a two-dimensional optomechanical crystal
• Silicon nanophotonics for scalable quantum coherent feedback networks