Solid Phase Crystallization (SPC) of a-Si Thin Film Induced by a Novel Approach for Photovoltaic Devices

Polycrystalline silicon has been widely investigated for their applications in the fabrication of thin film transistors (TFTs) and solar cell devices. For this application, large grain size and high quality of polycrystalline silicon are required to achieve high electron-hole mobility which is critical issue for better performance. Solid phase crystallization (SPC) is a highly promising method because of not only its simplicity and low cost but also its ability to produce a smooth interface and excellent uniformity with a high reproducibility. SPC process at 600°C, however, usually requires a long annealing time of over 20-60h to transform polycrystalline phase with large grain size, making it difficult for manufacturing. In this study, Solid phase crystallization (SPC) of amorphous silicon thin films by a novel modification of the nucleation step was investigated at low temperature. The thin film consists of high quality crystalline nanoparticles embedded in an amorphous matrix which can act as nuclei, resulting in a lower thermal energy for the nucleation. A novel modification in the nucleation step which can lead to enhance the crystallization of amorphous silicon thin film is proposed for the fabrication of photovoltaic silicon based devices. Consequently, the poly-Si thin film crystallized by a novel modification not only indicated better performance but also significantly reduced the crystallization time and processing temperature as compared to those crystallized without any treatments