Measurement of the IR absorption induced by visible radiation in amorphous silicon and silicon carbide thin films by an in-guide technique

Photoinduced absorption (PA) upon visible radiation (612 nm) has been studied at the wavelength of 1.55 μm in thin a-Si:H and a-SiC:H films fabricated by plasma enhanced chemical vapour deposition onto silicon wafers. Measurements were carried using a recently described in-guide technique. Several a-Si1−xCx:H/ZnO planar waveguides were fabricated in which the a-Si1−xCx:H cores differ in doping and carbon concentration. The in-guide technique confers high sensitivity to the measurements allowing the collection of data at illumination intensities as low as 150 μW/mm2. The phenomenon is highly enhanced by boron doping and quenched by the presence of carbon in the alloy.