Laser enhanced gettering of silicon substrates

详细信息    查看全文

• 作者：Daniel Chen ; Matthew Edwards ; Stuart Wenham ; Malcolm Abbott…
• 关键词：gettering ; multicystaline ; silicon ; impurities ; laser doping
• 刊名：Frontiers in Energy
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：11
• 期：1
• 页码：23-31
• 全文大小：476 KB
• 刊物类别：Engineering
• 刊物主题：Chinese Library of Science
  Energy Technology
  
• 出版者：Higher Education Press, co-published with Springer-Verlag GmbH
• ISSN：2095-1698
• 卷排序：11

文摘

One challenge to the use of lightly-doped, high efficiency emitters on multicrystalline silicon wafers is the poor gettering efficiency of the diffusion processes used to fabricate them. With the photovoltaic industry highly reliant on heavily doped phosphorus diffusions as a source of gettering, the transition to selective emitter structures would require new alternative methods of impurity extraction. In this paper, a novel laser based method for gettering is investigated for its impact on commercially available silicon wafers used in the manufacturing of solar cells. Direct comparisons between laser enhanced gettering (LasEG) and lightly-doped emitter diffusion gettering demonstrate a 45% absolute improvement in bulk minority carrier lifetime when using the laser process. Although grain boundaries can be effective gettering sites in multicrystalline wafers, laser processing can substantially improve the performance of both grain boundary sites and intra-grain regions. This improvement is correlated with a factor of 6 further decrease in interstitial iron concentrations. The removal of such impurities from multicrystalline wafers using the laser process can result in intra-grain enhancements in implied open-circuit voltage of up to 40 mV. In instances where specific dopant profiles are required for a diffusion on one surface of a solar cell, and the diffusion process does not enable effective gettering, LasEG may enable improved gettering during the diffusion process.