Thermal lens and non-linear optical absorption study of a-SiH films

Thermal effects on optical properties and non-linear optical absorption have been studied in hydrogenated amorphous silicon films using dual beam thermal lens technique. A change of the thermal lens signal, from positive to negative, with increase of the excitation power at some wavelengths, has been observed. The thermal conductivity and thermal diffusivity were K = (2.6 ± 0.1) × 10−3 W/cm K and D = (1.9 ± 0.1) × 10−3 cm2/s, respectively. Moreover, we observed a decay in the transmission signal, which was fit with two exponential functions, related to thermal effects, and competition between the creation of photo induced defects and their thermal annealing.