Microscopic Distributions of Light Elements and Their Precipitates in Multicrystalline Silicon for Solar Cells

Abstract

The behaviors of carbon, nitrogen, and oxygen in multicrystalline silicon grown by the cast method were investigated using infrared absorption spectroscopy. A microscopic distribution map of the impurities and their precipitates was obtained with a spatial resolution of a few tens of µm. The distribution and bonding states depended on the impurity: nitrogen and oxygen precipitated as crystalline nitride (α-Si3N4) and amorphous oxide (SiO2), respectively, while carbon distributed homogeneously as isolated substitutional atoms. The nitrogen and oxygen precipitates remained independent, and thus, they might not have formed a compound oxynitride like Si2N2O.

Formation of Si2N2O Microcrystalline Precipitates near the Quartz Crucible Wall Coated with Silicon Nitride in Cast-Grown Silicon

“…The existence of the Si 2 N 2 O phase of silicon oxynitride in multicrystalline Si was previously suggested. [7][8][9][10] However, it has not yet been determined whether these precipitates are amorphous or crystalline and whether their stoichiometry is in fact Si 2 N 2 O. In the present study, we show crucial evidence of the formation of stoichiometric Si 2 N 2 O microcrystalline precipitates inside of the Si ingot.…”

Impact of Light-Element Impurities on Crystalline Defect Generation in Silicon Wafer

“…The relationship between crystalline defects and chemical bonding of light-element impurities, such as carbon, nitrogen, and oxygen in mc-Si wafer, has been reported. [17][18][19] However, the behavior and impact of light-elements during crystal growth is not well understood yet. We believe it is necessary to clarify the effects of impurities on crystal growth to improve crystal quality.…”

Impact of light element impurities on crystalline defect generation in silicon substrate

“…These imperfections act as minority carrier recombination center and degrade the conversion efficiency of solar cells [1]. On the other hand, although it is reported the chemical bonding of light element impurities, such as C, N, and O in multi-crystalline silicon substrate [2], the behavior of light element during crystalline growth is not well understood yet. We consider it is necessary to clarify the impurity effect on the crystalline growth to improve the crystal quality.…”