Novel Precursor Deposition Method for Inline Diffusion

In this paper we present a new method for deposition of precursors, here diluted phosphoric acid, on silicon wafers for the purpose of inline diffusion. The method consists of a surface preparation step to enhance wettability followed by the actual coating step. Coating is carried out by rolling the precursor onto the wafers with a set of sponge rollers. This approach results in homogenous deposition of thin precursor layers without the need for adding surfactants or organic solvents. We demonstrate that the novel precursor deposition method, in conjunction with an appropriate diffusion process, is suitable for preparation of very homogeneous emitters exhibiting depth profiles similar to POCl3 emitters. Cell efficiency of first processed multi-crystalline solar cells was 15.2% in average and 15.6% for the best cell.