Growth of carbon and nitrogen containing precipitates in crystalline solar silicon and their influence on solar cells

Abstract

The growth mechanisms, structural, mechanical, and electrical properties of silicon carbide and silicon nitride precipitates in solar silicon are reviewed and some new aspects about the distribution of trace elements in these precipitates are reported in this review. SiC and Si3N4 precipitates may have detrimental impact on the quality of solar silicon material. Therefore intensive research has been done at these precipitates in the past, which is summarized first. The properties of the different types of precipitates reported in literature are then described in detail. Especially SiC precipitates may have detrimental impact on the electrical behavior of solar cells by causing severe ohmic shunting. Furthermore SiC precipitates are very hard and may harm the wafering process. An outlook of the impact of such precipitates on new cell concepts and new solar silicon materials, such as n‐type, is given.

Defect engineering in cast mono‐like silicon: A review

“…When the concentration of carbon exceeds its solubility in silicon during the crystal growth, it will precipitate in the form of silicon carbide (SiC), which can cause severe ohmic shunting across the p‐n junction. The precipitates of SiC typically have two forms—particles and filaments in cast mono‐like silicon 68 . The SiC filaments are <5 μm in diameter but up to 3 mm in length 68,69 .…”

“…The precipitates of SiC typically have two forms—particles and filaments in cast mono‐like silicon 68 . The SiC filaments are <5 μm in diameter but up to 3 mm in length 68,69 . The SiC filaments mostly grow in GBs and in the direction of crystallization direction 69 .…”

“…The SiC filaments mostly grow in GBs and in the direction of crystallization direction 69 . The SiC filaments are typically doped with N impurity at the concentration of 1.3–2.8 × 10 21 atoms/cm 3 and hence are n‐type 68,69 . Because of the high N doping in the SiC filaments, the SiC filaments can be a low‐resistant shunting path for cast mono‐like silicon solar cells.…”

“…The SiC particles are also highly doped with N impurity at the concentration of ~10 21 atoms/cm 3 ; however, because of the small length of the SiC particles, they are less likely to cause shunting problem 68 . In addition, the SiC particles mostly grow within grain volume and around the Si 3 N 4 rod 68 . More information about the SiC precipitates in cast mono‐like silicon can be found elsewhere 68–70 .…”

Pss − Looking Into a Bright Future

“…Moreover, we published a Special Issue on “Single‐Electron Control in Solid State Devices” in pss (b) guest edited by Janine Splettstoesser and Rolf J. Haug . On the occasion of the 10th anniversary of pss (RRL) we presented a series of invited Review@RRL . Bernd Büchner, Rudi Hackl, and Dirk Johrendt edited a Special Issue on “High‐Temperature Superconductivity in Iron‐Based Compounds”, consisting of results that were obtained in the Priority Program SPP 1458 funded by the German Research Foundation.…”