Simulation of emitter doping profiles formed by industrial POCl3 processes

This paper quantifies the recombination losses associated with industrial POCl₃ emitters. We examine three standard (STD) recipes and four of DuPont´s lightly doped emitter (LDE) recipes. We find that an STD emitter has a higher effective surface recombination velocity than an LDE recipe of the same sheet resistance because it has a higher surface concentration. More significantly, we find that STD emitters have greater SRH recombination within the doped region, probably because they contain a greater concentration of inactive phosphorus atoms which are known to form silicon phosphide precipitates. These conclusions are drawn from simulations and experiments on the lifetime of test wafers and the quantum efficiency of solar cells. It is shown how this data can be used to distinguish the SRH recombination that occurs at the surface from the SRH that occurs inside an emitter.