INFLUENCE OF IRON AND CHROMIUM BULK CONTAMINATION ON THE PERFORMANCES OF P-TYPE BORON DOPED SINGLE-CRYSTALLINE SILICON SOLAR CELLS

摘要

This paper focuses on the influence of iron and chromium bulk contamination on the performances of p-type boron-doped single-crystalline silicon solar cells, in order to determine the metal concentration threshold which can be tolerated, taking into account the state of the impurity in silicon, the eventual injection level dependence of the bulk lifetime, and the processing steps. Solar cells were manufactured according to a standard industrial process from iron and chromium intentionally contaminated single-crystalline silicon wafers (Cz and FZ). The efficiency of gettering and hydrogenation effects toward iron are quantified and then introduced in numerical simulations to compute the evolution of the solar cell conversion efficiency as a function of the dissolved iron concentration. In conclusion iron and chromium are transition-metal impurities rather well tolerated in single-crystalline silicon, mainly due to the efficiency of the gettering effects (occurring during the phosphorus diffusion and the Al-Si alloy formation), and to a lesser extent, due to hydrogenation effects in FZ silicon wafers.