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

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 mum. The experimental data have been fitted using a single-oscillator model that takes into account the shape of the epsilon (2) 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.