Laser Annealing and Local Heating Effects during Raman Measurement of Hydrogenated Amorphous Silicon Films

Two possible side effects when evaluating the crystalline volume fraction of microcrystalline silicon films by Raman spectroscopy measurement have been investigated. Large laser power incident into the microcrystalline silicon film during measurement may cause some amorphous to crystalline phase transition. In addition, the local temperature rise during measurement also leads to some spectrum shift. Both effects results in incorrect or inaccurate evaluation of microcrystalline silicon film crystallinity. By changing the laser power during amorphous silicon film Raman measurement, it is found that the critical power density to induce crystallization of amorphous silicon is ~455kW/cm2. Furthermore, red-shift of the Raman peak due to local heating effect is observed.