Sprayed boric acid as a dopant source for silicon ribbons

This paper presents a new method for bulk boron doping of silicon ribbons for solar cells. The method is based on the spraying of the ribbon with a solution of boric acid followed by zone melting recrystallization in an argon atmosphere. Dopant incorporation is evaluated by measuring the spreading resistance of the silicon ribbon. rical model for the incorporation of boron into silicon was developed, considering two competing mechanisms: boron diffusion during the heating step and evaporated boron transport in the gas phase. The dependence of the incorporation of boron on experimental parameters such as the direction of recrystallization and the flux of argon in and out of the furnace was measured, yielding results that are compatible with the numerical model. It is also shown that the mean incorporation of boron into the samples depends linearly on the initial concentration of boric acid.