Effect of trimethylsilane flow rate on the growth of SiC thin-films for fiber-optic temperature sensors

Abstract

We have investigated the effect of trimethylsilane ([(CH/sub 3/)/sub 3/SiH] or 3MS) flow rate on the growth of SiC thin-film on single-crystal sapphire substrate for fiber-optic temperature sensor. The SiC film thickness was in the range of 2-3 /spl mu/m. The variation of the 3MS flow rate affected the structural properties of the SiC films. This, in turn, changed the optical properties and temperature sensing performance of the sensors. Optical reflection from the SiC thin-film Fabry-Pe/spl acute/rot interferometers showed one-way phase shifts in resonant minima on all measured samples. Linear fits to the resonant minima (at 660 to 710 nm) versus temperature provide the corresponding thermal expansion coefficient, /spl kappa//sub /spl phi//, of 1.7-1.9/spl times/10/sup -5///spl deg/C. With the optimized 3MS flow rate, the SiC temperature sensor exhibits a temperature accuracy of /spl plusmn/2.8/spl deg/C from 22 to 540/spl deg/C. The short-term SiC sensor stability at 532/spl deg/C for two weeks shows a very small standard deviation of 0.97/spl deg/C.