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

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Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon. / Pasanen, Toni P.; Laine, Hannu; Vähänissi, Ville; Salo, Kristian; Husein, Sebastian; Savin, Hele.

In: IEEE Journal of Photovoltaics, Vol. 8, No. 3, 19.03.2018, p. 697-702.

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@article{5dff0e0a083b440babe92a4b94bdff91,
title = "Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon",
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.",
keywords = "black silicon, etching, nanostructure, phosphorus emitter, RCA clean, standard clean",
author = "Pasanen, {Toni P.} and Hannu Laine and Ville V{\"a}h{\"a}nissi and Kristian Salo and Sebastian Husein and Hele Savin",
year = "2018",
month = "3",
day = "19",
doi = "10.1109/JPHOTOV.2018.2806298",
language = "English",
volume = "8",
pages = "697--702",
journal = "IEEE Journal of Photovoltaics",
issn = "2156-3381",
number = "3",

}

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TY - JOUR

T1 - Impact of Standard Cleaning on Electrical and Optical Properties of Phosphorus-Doped Black Silicon

AU - Pasanen, Toni P.

AU - Laine, Hannu

AU - Vähänissi, Ville

AU - Salo, Kristian

AU - Husein, Sebastian

AU - Savin, Hele

PY - 2018/3/19

Y1 - 2018/3/19

N2 - 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.

AB - 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.

KW - black silicon

KW - etching

KW - nanostructure

KW - phosphorus emitter

KW - RCA clean

KW - standard clean

U2 - 10.1109/JPHOTOV.2018.2806298

DO - 10.1109/JPHOTOV.2018.2806298

M3 - Article

VL - 8

SP - 697

EP - 702

JO - IEEE Journal of Photovoltaics

JF - IEEE Journal of Photovoltaics

SN - 2156-3381

IS - 3

ER -

ID: 18388858