Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

Toni P. Pasanen, Hannu Laine, Ville Vähänissi, Kristian Salo, Sebastian Husein, Hele Savin

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)
163 Downloads (Pure)

Abstract

Black silicon (b-Si) has been estimated to considerably grow its market share as a front texture of high-efficiency silicon solar cells. In addition to excellent optical properties, high-efficiency cell process requires extreme cleanliness of the bulk material, and thus cleaning of b-Si surfaces is often a critical process step. While standard clean (SC) 1 solution efficiently removes possible contamination from wafer surfaces, we show here that it may cause challenges in b-Si solar cells. First, the silicon etch rate in SC1 solution is shown to depend on the phosphorous concentration and as high rate as ∼1.4 nm/min is observed on planar emitter surfaces. When extending the study to b-Si, which has much larger surface area in contact with the cleaning solution, even higher volumetric Si consumption occurs. This is observed in significant changes in emitter doping profiles, for instance, a 10 and 30-min cleaning increases the sheet resistance from 47 to 57 Ω/□ and 127 Ω/□, respectively. Furthermore, the SC1 solution alters substantially the nanostructure morphology, which impacts the optics by nearly doubling and more than tripling the surface reflectance after a 30 and 60-min immersion, respectively. Thus, uncontrolled cleaning times may impair both the electrical and optical properties of b-Si solar cells.
Original languageEnglish
Pages (from-to)697-702
Number of pages6
JournalIEEE Journal of Photovoltaics
Volume8
Issue number3
Early online date19 Mar 2018
DOIs
Publication statusPublished - 19 Mar 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • black silicon
  • etching
  • nanostructure
  • phosphorus emitter
  • RCA clean
  • standard clean

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  • Projects

    Black silicon and defect engineering for highly efficient solar cells and modules, BLACK

    Savin, H., Laine, H., Yli-Koski, M., Vähänissi, V., Liu, Z., Haarahiltunen, A., Modanese, C., Pasanen, T., Heikkinen, I. & von Gastrow, G.

    01/03/201531/08/2018

    Project: Business Finland: Other research funding

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    OtaNano

    Anna Rissanen (Manager)

    Aalto University

    Facility/equipment: Facility

  • Activities

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    Impact of standard cleaning on electrical and optical properties of phosphorus-doped black silicon

    Toni Pasanen (Contributor), Hannu Laine (Contributor), Ville Vähänissi (Contributor), Kristian Salo (Contributor), Hele Savin (Invited speaker)
    18 Jun 2018

    Activity: Talk or presentation typesPublic or invited talk

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