Low-Loss Nanophotonic Devices with Chip-Level Uniformity and Integrated Color Centers in SiC-On-Insulator
Jason Lipton, Brett Yurash, Adam Sorensen, John J. Vajo, Samuel J. Whiteley, Tong Wang, Biqin Huang, Xiwei Bai, Adrian Portales, Sam Rubin, Judas Strayer, Jason Graetz, Shanying Cui
Abstract
4H–SiC is a promising material platform for quantum photonic integrated circuits due to its wide bandgap, high refractive index, and variety of optically addressable defects, while being compatible with CMOS fabrication processes. However, it is currently not possible to fabricate chip-scale photonic integrated circuits with integrated color centers due to nonuniformity of SiC thickness arising from the SiC-on-insulator fabrication process. We apply the concept of dopant-selective photoelectrochemical etching to a SiC-on-insulator stack for a highly effective total thickness variation (TTV) reduction. We show a reduction of SiC TTV by a factor of 7 through selectively etching a high-TTV sacrificial n-type layer, to stop on an epitaxially defined intrinsic layer. Fabricated photonic devices on selectively etched SiCOI exhibit a high yield of optical elements while maintaining a record low propagation loss for 920 nm single-mode optical elements in SiC (2 dB/cm). Finally, we show etch process compatibility with color centers through the measurement of zero phonon line emission from ensemble divacancy defects into our fabricated waveguides. This work represents the first successful demonstration of a TTV reduction method in SiCOI that is compatible with color center emission, marking a significant advancement toward scalable 4H–SiC-on-insulator integrated photonics for quantum technologies.