Optimizing Emitter Diffusion Process for Atmospheric Pressure Dry Nanotextured Monocrystalline PERC

In this article, we present an optimization of the emitter diffusion for nanotextured p-type monocrystalline silicon solar cells using atmospheric pressure dry etching (ADE) in conjunction with a post-ADE short acidic etch in a passivated emitter and rear cell (PERC) architecture. The optimization of the phosphorus oxychloride diffusion process was realized by first investigating the emitter sheet resistance and emitter recombination current density to achieve improved electrical properties and cell performances at a later stage. The optimization of the diffusion process enables an excellent homogeneity for emitter sheet resistance of 105 omega/sq with minimized standard deviation of 3%, a decreased emitter saturation current density of similar to 120 fA/cm2, a peak doping concentration of 2.2 x 1020 cm-3 and depth of the highly doped surface region of 20 nm, still in the range that is required for good contact formation. By step optimization of the emitter formation of ADE textured PERC solar cells, an efficiency improvement of 0.6% $_\text{abs}$ could be reached leading to best conversion efficiency of 20.9%.

Automated summary

This article presents an optimization of emitter diffusion for nanotextured p-type monocrystalline silicon solar cells using atmospheric pressure dry etching and a short acidic etch, resulting in improved electrical properties and cell performances, ultimately leading to a 20.9% conversion efficiency.