Simulation of phase changes and dopant diffusion in silicon for the manufacturing of selective phosphorous emitters via laser chemical processing
In this paper we report progress in the simulation of Laser Chemical Processing (LCP) with respect to the selective emitter forming. Our existing Matlab® code for simulation of laser heating, melting and evaporation has been enhanced to take into account evaporation by nanosecond pulses, dopant diffusion in silicon melt and the influence of the increased ambient pressure, caused by the high velocity liquid jet impinging on the surface. The new models have been uccessfully tested and compared with dry laser doping experiments. For the LCP case we achieved good agreement between simulation and experiment only for laser pulses in the nanosecond regime, because only for these process parameters hydrodynamic effects caused by the liquid jet can be neglected. From these results we can conclude that the best solar cell performance with LCP doping is achieved if the dominant dopant transport mechanism is liquid phase diffusion.