Study of re-crystallization processes in amorphous silicon films

Technology of amorphous hydrogenated silicon (a-Si:H) thin films is a subject of interest of many researchers. This paper deals with the re-crystallization processes in a-Si:H thin films prepared by plasma enhanced chemical vapour deposition (PECVD) using a SAMCO PD-220N unit. Evaluation of crystallization process was monitored in a high temperature chamber AP1200 by using “in-situ” X-ray diffraction (XRD). The experiments have given information about phase transformation from the amorphous to polycrystalline phase and were carried out at temperatures in the range of 580°C to 620°C. The average crystalline size of crystallized films was found from 40 to 50 nm. Structural properties of the initial amorphous and re-crystallized films were also investigated by Raman spectroscopy. Optical properties (refractive indices, extinction coefficients) of a-Si:H and poly-Si films were analyzed by UV Vis spectrophotometry. The absorption properties of the films were carried out from the UV Vis experimental data.