High-Q suspended optical resonators in 3C silicon carbide obtained by thermal annealing
We fabricate suspended single-mode optical waveguides and ring resonators in 3C silicon carbide (SiC) that operate at telecommunication wavelength, and leverage post-fabrication thermal annealing to minimize optical propagation losses. Annealed optical resonators yield quality factors of over 41,000, which corresponds to a propagation loss of 7 dB/cm, and is a significant improvement over the 24 dB/cm in the case of the non-annealed chip. This improvement is attributed to the enhancement of SiC crystallinity and a significant reduction of waveguide surface roughness, from 2.4 nm to below 1.7 nm. The latter is attributed to surface layer oxide growth during the annealing step. We confirm that the thermo-optic coefficient, an important parameter governing high-power and temperature-dependent performance of SiC, does not vary with annealing and is comparable to that of bulk SiC. Our annealing-based approach, which is especially suitable for suspended structures, offers a straightforward way to realize high-performance 3C-SiC integrated circuits.
© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. Received 7 Nov 2019; revised 3 Jan 2020; accepted 27 Jan 2020; published 7 Feb 2020. This work was carried out at the Harvard Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN). The authors would like to thank Guixiong Zhong at CNS for carrying out XRD measurements, Jianfu Wang, Liwei Li and Michael Collins from the University of Sydney for their help with optical waveguides and annealing techniques. Funding" University of Sydney (Sydney Research Accelerator Fellowship, Harvard University Mobility Scheme, Research Training Program Scholarship); Natural Sciences and Engineering Research Council of Canada (INQNET Research Program); U.S. Department of Energy (DE-SC0019219). The authors declare that there are no conflicts of interest related to this article.
Published - oe-28-4-4938.pdf