Efficient thermo-optic micro-ring phase shifter made of PECVD silicon-rich amorphous silicon carbide

In this work, the thermo-optic coefficient (TOC) of the silicon-rich amorphous silicon carbide (a-SiC) thin film deposited by plasma-enhanced chemical vapor deposition is characterized. We found that the TOC of the film increases as its silicon content increases. A more than three-fold improvement in the TOC is measured, reaching a TOC as high as $1.88 \times 10^{-4} K^{-1}$, which is comparable to that of crystalline silicon. An efficient thermo-optic phase shifter has also been demonstrated by integrating the silicon-rich a-SiC micro-ring structure with a NiCr heater. Its tuning efficiency $P_{\pi}$ as low as 4.4 mW has been measured at an optical wavelength of 1550 nm. These findings make silicon-rich a-SiC a good material candidate for thermo-optic applications in photonic integrated circuits.