Black silicon significantly enhances phosphorus diffusion gettering

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • Fraunhofer Institute for Solar Energy Systems ISE

Abstract

Black silicon (b-Si) is currently being adopted by several fields of technology, and its potential has already been demonstrated in various applications. We show here that the increased surface area of b-Si, which has generally been considered as a drawback e.g. in applications that require efficient surface passivation, can be used as an advantage: it enhances gettering of deleterious metal impurities. We demonstrate experimentally that interstitial iron concentration in intentionally contaminated silicon wafers reduces from 1.7 × 1e13 cm−3 to less than 1e10 cm−3 via b-Si gettering coupled with phosphorus diffusion from a POCl3 source. Simultaneously, the minority carrier lifetime increases from less than 2 μs of a contaminated wafer to more than 1.5 ms. A series of different low temperature anneals suggests segregation into the phosphorus-doped layer to be the main gettering mechanism, a notion which paves the way of adopting these results into predictive process simulators. This conclusion is supported by simulations which show that the b-Si needles are entirely heavily-doped with phosphorus after a typical POCl3 diffusion process, promoting iron segregation. Potential benefits of enhanced gettering by b-Si include the possibility to use lower quality silicon in high-efficiency photovoltaic devices.

Details

Original languageEnglish
Article number1991
Pages (from-to)1-6
Number of pages6
JournalScientific Reports
Volume8
Publication statusPublished - 31 Jan 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Materials for devices, Semiconductors, Solar energy and photovoltaic technology

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