Phosphorous-Doped α -Si Film Crystallization Using Heat-Assisted Femtosecond Laser Annealing

摘要

Heat effects on femtosecond laser annealing to crystallize doped amorphous Si films are studied. The structural, optical and electronic properties of phosphorus-doped amorphous Si films before and after femtosecond laser treatment are characterized. As the temperature increases from room temperature to 200 degrees C controlled by a hot-stage, the grain size and number of crystalline Si on the films are gradually enhanced, which is confirmed by comparing the surface morphologies and analyzing the Raman spectrum. It is demonstrated that heating the substrate can promote the phase transformation of amorphous Si and the activation of phosphorus dopants, yielding a significant improvement in the light-trapping capability and carrier conductivity of the laser-annealed films. By using the proposed heat-assisted femtosecond laser annealing technique, polycrystallized phosphorus-doped amorphous Si films are produced showing highly absorptive and conductive, which might be further applied in photovoltaic and microelectronic devices.