INSITU DETERMINATION OF OPTICAL-CONSTANTS OF GROWING HYDROGENATED AMORPHOUS-SILICON FILM BY P-POLARIZED LIGHT REFLECTANCE MEASUREMENT ON THE SURFACE

The reflection of p-polarized laser light was monitored in situ to elucidate the surface reaction process in plasma chemical vapor deposition of a-Si:H. The reflectance oscillated with the film growth. The deposition rate, refractive index, and absorption coefficient of the film were evaluated so that the detected reflectance oscillation could be best fitted with the pattern calculated by using the thickness and optical constants of the growing film as variable parameters. The deposition rate was unchanged by the variation of substrate temperature in the range between room temperature and 250-degrees-C, whereas the refractive index and absorption coefficient increased with the substrate temperature in this range. The presence of a loosely packed layer as thick as 5 nm was clearly indicated by the analysis of time-dependent reflectance variation.