Characterizing the Influence of Crystal Orientation on Surface Recombination in Silicon Wafers

We present two approaches for evaluating the influence of crystal orientation on surface passivation of silicon wafers using photoluminescence imaging. The methods allow a variety of orientations that are not limited to (100) and (111) planes to be studied. The first approach is based on imaging carrier lifetimes in silicon strips containing different surface orientations that have been created from a single monocrystalline silicon wafer via laser cutting. The second approach is based on imaging carrier lifetimes among different grains in multicrystalline silicon wafers, which make use of their random distribution of crystal orientations. Both approaches are demonstrated with silicon-oxide-passivated samples. The results from both methods are consistent with each other, showing that the studied silicon oxide films provide a better passivation on surfaces with higher surface energy, such as (100) or (106) surfaces, compared with those with lower surface energy, such as (235) or (1 1 1) surfaces. The advantages and limitations of both approaches are also discussed and compared.