The Effect of DC Bias Voltage on the Structural and Optical Properties of Hydrogenated Nanocrystalline Si Thin Films

Amorphous and nanocrystalline Si films were prepared by plasma enhanced chemical vapor deposition (PECVD). The films were deposited with a RF power of 100 W, while substrates were under DC biases varying from 0 to -600 V. The size as well as the concentration of Si nanocrystallites increased with raising the DC bias; the PL emission wavelength was shifted from 400 to 750 nm. A model for the nanostructural variation in the nc-Si:H films was suggested to describe the change in the size and concentration of the nanocrystallites as well as the amorphous matrix depending on the DC bias conditions.