Oxygen precipitates distributed around random grain boundaries in a cast-grown multicrystalline silicon crystal

Abstract

We investigated oxygen precipitates and grain boundaries (GBs) in multicrystalline silicon for solar cells. We observed the distribution of GBs on both sides of the specimen by using an electron backscattering pattern to be able to compare it with the distribution of oxygen precipitates revealed by infrared absorption spectroscopy. We precisely examined the relationship between oxygen precipitates and various GBs, which are coincidence site lattice GBs ( ) and random GBs, and found that the distribution of oxygen precipitates coincided with that of random GBs. Furthermore, we annealed the specimen in which the oxygen precipitates already existed around the random GBs, and found that the dispersion and coalescence of the precipitates took place.

Distribution of light-element impurities in Si crystals grown by seed-casting method

“…Control of these light-element impurities, i.e., interstitial oxygen (O i ) and substitutional carbon (C s ), has become essential because light-element impurities affect solar sell performance through defect formation. [17][18][19][20][21][22][23][24][25][26][27] It is necessary to accurately clarify the mechanism of generation of the light-element impurities in Si crystals grown by the seed-casting method to develop methods to suppress the degradation in solar cell efficiency.…”