Laser Doping and Recrystallization for Amorphous Silicon Films by Plasma-Enhanced Chemical Vapor Deposition

Abstract

One of the most challenging problems to develop polycrystalline silicon thin-film solar cells is the growth of crystalline silicon on foreign, low-cost and low-temperature substrates. In this paper, a laser doping technique was developed for the plasma-deposited amorphous silicon film. A process combination of recrystallization and dopant diffusion (phosphorous or boron) was achieved simultaneously by the laser annealing process. The doping precursor was synthesized by a sol-gel method and was spin-coated on the sample. After laser irradiation, the grain size of the doped polycrystalline silicon was examined to be about 0.5~1.0 µm. The concentrations of 2×1019 and 5× 1018 cm-3 with Hall mobilities of 92.6 and 37.5 cm²/V-s were achieved for the laser-diffused phosphorous- and boron-type polysilicon films, respectively.