title: Fabrication of High-Q Nanobeam Photonic Crystals in Epitaxially Grown 4H-SiC.
abstract: Silicon carbide (SiC) is an intriguing material due to the presence of spin-active point defects in several polytypes, including 4H-SiC. For many quantum information and sensing applications involving such point defects, it is important to couple their emission to high quality optical cavities. Here we present the fabrication of 1D nanobeam photonic crystal cavities (PCC) in 4H-SiC using a dopant-selective etch to undercut a homoepitaxially grown epilayer of p-type 4H-SiC. These are the first PCCs demonstrated in 4H-SiC and show high quality factors (Q) of up to ∼7000 as well as low modal volumes of <0.5 (λ/n)(3). We take advantage of the high device yield of this fabrication method to characterize hundreds of devices and determine which PCC geometries are optimal. Additionally, we demonstrate two methods to tune the resonant wavelengths of the PCCs over 5 nm without significant degradation of the Q. Lastly, we characterize nanobeam PCCs coupled to luminescence from silicon vacancy point defects (V1, V2) in 4H-SiC. The fundamental modes of two such PCCs are tuned into spectral overlap with the zero phonon line (ZPL) of the V2 center, resulting in an intensity increase of up to 3-fold. These results are important steps on the path to developing 4H-SiC as a platform for quantum information and sensing.
authors: Department of Physics and ‡School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors: David O
authors: DO
authors: Bracher
authors: Department of Physics and ‡School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors: Evelyn L
authors: EL
authors: Hu
keywords: Silicon carbide; mode tuning; nanobeam photonic crystals; photonic crystal cavities; point defects