Study of the thermo-optic effect in hydrogenated amorphous silicon and hydrogenated amorphous silicon carbide between 300 and 500 K at 1.55 μm

The thermo-optic coefficients of hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon carbide (a-SiC:H)—two of the main amorphous semiconductors in optoelectronics—have been measured and critically analyzed in the practical device operation temperature range 300–500 K, at the communication wavelength of 1.55 μm. The experimental data have been fitted using a single-oscillator model that takes into account the shape of the ε2 spectrum of the amorphous materials. In particular, for a-Si:H, the extracted parameters significantly extend, and are consistent with, the few data reported in the literature; an interesting analogy with crystalline silicon is also found and discussed. Complete results for a-SiC:H are finally reported.