Temperature-dependent optical properties of silicon carbide for wireless temperature sensors
Abbreviated Journal Title
J. Phys. D-Appl. Phys.
3C-SILICON CARBIDE; OXIDATION; DEVICES; REFLECTIVITY; POLYTYPES; Physics, Applied
The temperature-dependent optical properties of materials, such as refractive index and reflectivity, can be used for remote sensing of temperatures using a laser beam. Wireless sensing mechanism eliminates the need for external electrical contacts to the sensor, typically required in electrical property-based sensors. Such contacts tend to melt at elevated temperatures. This paper investigates the optical response of silicon carbide to temperature changes, indicating the potential for realizing silicon carbide-based high temperature wireless sensors by using a helium-neon laser of wavelength 632.8 nm. The laser power reflected by single crystal 6H-silicon carbide substrates has been measured at different temperatures up to 750 degrees C. The reflected powers exhibited oscillatory patterns caused by multiple beam interference for which the substrate itself acts as a Fabry-Perot etalon. These results were used to calculate the refractive index, reflectivity and thermo-optic coefficients of silicon carbide as a function of temperature. Two samples with different dopant profiles were investigated to examine the effects of dopants on the optical response of silicon carbide substrates. With proper modification of the microstructure in the substrate, the temperature dependence of reflectivity can be used directly to measure temperature remotely.
Journal of Physics D-Applied Physics
"Temperature-dependent optical properties of silicon carbide for wireless temperature sensors" (2007). Faculty Bibliography 2000s. 7000.