Integrated photonic devices with silicon oxycarbide

Abstract

In this paper, we report on the potential of silicon oxycarbide (SiOC) for integrated photonic applications. SiOC films are developed by reactive radio frequency magnetron sputtering from a silicon carbide (SiC) target in the presence of argon and oxygen gases. The optical properties of the developed SiOC film are characterized with spectroscopic ellispometry over a broad wavelength range 300-1600 nm. The refractive index n of the SiOC film is 2.2 at wavelength λ = 1550 nm and the extinction coefficient k is estimated to be less than 10-4 in the near-infrared region above 600 nm. The topography of SiOC films is studied with AFM showing very smooth surface, with rms roughness of 0.24 nm. SiOC film with refractive index n = 2.2 is then patterned by direct laser-writing lithography and etched with reactive ion etching to realize high contrast SiOC core optical waveguides for integrated photonics applications. The waveguide losses are characterized at telecommunication wavelength λ = 1550 nm. As an example of photonic integrated devices integrating SiOC films, a microring resonator is fabricated where a SIOC layer is used as a coating material for the core of a silicon oxynitride (SION) waveguide.

High Thermo-Optic Coefficient of Silicon Oxycarbide Photonic Waveguides

“…Silicon oxycarbide (SiOC) is a novel class of glass compounds that has gained momentum in the scientific community and adopted in technologically important applications such as interlayer dielectrics, anode material in lithium-ion batteries, and photoluminescence. − Recently, we have introduced SiOC as a potential platform in integrated photonics. , The refractive index of SiOC can be tailored from n = 1.45, corresponding to SiO 2 , to about 3.2, for amorphous SiC. − SiOC has the advantage of a low absorption coefficient in the near-infrared region, and low-loss waveguides on silica realized by sputtering have been demonstrated for the first time with a core index of 1.578 and 2.2. , Waveguide attenuation of 2 to 4 dB/cm in the telecom window of 1550 nm has been measured. In comparison with SiON, exhibiting a pronounced absorption peak around 1505 nm due to N–H bonds, SiOC absorption is spectrally flat across the full (S, C, L) telecom bands, offering a tremendous advantage for broadband applications.…”

“…The SiOC film was deposited on a silicon wafer with a 6 μm thick silica substrate by using reactive radio frequency (RF) magnetron sputtering from a SiC target in an oxygen and argon atmosphere. Details on the SiOC sputtering procedure can be found in previous publications. , X-ray photoelectron spectroscopy (XPS) measurements revealed that the deposited material contains 45% silicon, 28% oxygen, and 27% carbon, so that the actual chemical composition is Si 0.45 O 0.27 C 0.27 (for brevity, in the remaining of the paper it will be simply referred to as SiOC omitting the subscripts). Good adhesion of the SiOC film on the silica substrate was observed, with no evidence of either pin holes or porosity.…”

“…The SiOC surface roughness, as estimated with atomic force microscopy (AFM), is as low as 0.24 nm rms, which is comparable to the silica substrate. The optical constants of the SiOC film were measured with a variable-angle spectroscopic ellipsometer over a broad spectral range from the UV to near-infrared regions . Around a wavelength of 1550 nm the measured refractive index of the SiOC layer is about 2.2 and the extinction coefficient is less than 10 –4 above 600 nm.…”

“…5−7 Recently, we have introduced SiOC as a potential platform in integrated photonics. 8,9 The refractive index of SiOC can be tailored from n = 1.45, corresponding to SiO 2 , to about 3.2, for amorphous SiC. 10−12 SiOC has the advantage of a low absorption coefficient in the near-infrared region, and low-loss waveguides on silica realized by sputtering have been demonstrated for the first time with a core index of 1.578 and 2.2.…”

“…10−12 SiOC has the advantage of a low absorption coefficient in the near-infrared region, and low-loss waveguides on silica realized by sputtering have been demonstrated for the first time with a core index of 1.578 and 2.2. 8,9 Waveguide attenuation of 2 to 4 dB/cm in the telecom window of 1550 nm has been measured. In comparison with SiON, exhibiting a pronounced absorption peak around 1505 nm due to N−H bonds, 1 SiOC absorption is spectrally flat across the full (S, C, L) telecom bands, offering a tremendous advantage for broadband applications.…”