Effects of laser irradiation on a diffused layer in silicon

High-temperature diffusion of boron or phosphorus into silicon leads to the formation of precipitates and/or dislocation loops in the diffused layer, which influence junction characteristics and limit the photovoltaic current and voltage response. It is shown that dislocation loops can be removed, precipitates can be dissolved, and the boron or phosphorus in them can be electrically activated by high-power ruby laser radiation. This serves to reduce the sheet resistance and improve the junction characteristics as well as the solar cell parameters.