Removing the effect of striations in n-type silicon solar cells

Coletti, Gianluca; Manshanden, P.; Bernardini, Simone; Bronsveld, P.C.P.; Gutjahr, A.; Zhiyan, Hu; Li, G.

doi:10.1016/j.solmat.2014.06.016

Cited by 36 publications

(18 citation statements)

References 17 publications

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“…N-type silicon has been long lauded for its low susceptibility to light-induced degradation such as boron-oxygen related degradation and the impact from metallic contaminants [19]. Although this material does indeed suffer from degradation induced by grown-in defects, which have been extensively studied [20], an investigation of LeTID on n-type silicon concluded that the defect either does not manifest itself or is not recombination active in ntype [17]. On the other hand, a study by Renevier et al demonstrated a carrier-induced instability in the lifetime of boron-diffused n-type wafers fired in the presence of a hydrogenrich dielectric when subject to either illuminated annealing or dark annealing [21].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen induced degradation: A possible mechanism for light- and elevated temperature- induced degradation in n-type silicon

Chen

Hamer

Kim

et al. 2018

Solar Energy Materials and Solar Cells

109

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In this work, we demonstrate a form of minority carrier degradation on ntype Cz silicon that affects both the bulk and surface related lifetimes. We identify three key behaviors of the degradation mechanism; 1) a firing dependence of degradation extent, 2) the appearance of bulk degradation when wafers are fired in the presence of a diffused emitter and 3) a firing related apparent surface degradation when wafers are fired in the absence of an emitter. We further report a defect capture cross-section ratio of σn/σp = 0.028 ± 0.003 for the defect in n-type. Utilizing our understanding of LeTID in p-type silicon, we demonstrate that the degradation behaviors in both n-type and p-type silicon are closely correlated. In light of numerous reports on the involvement of hydrogen the potential role of a hydrogen-induced degradation mechanism is discussed in both p-and n-type silicon, particularly in relation to the diffusion of hydrogen and influence of hydrogen-dopant interactions.

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Section: Introductionmentioning

confidence: 99%

Hydrogen induced degradation: A possible mechanism for light- and elevated temperature- induced degradation in n-type silicon

Chen

Hamer

Kim

et al. 2018

Solar Energy Materials and Solar Cells

109

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show abstract

“…In conventional, horizontal cut wafers, these are the causes of ring-like structures reported in other studies. [25,26] A square-like artifact in the middle of A2 of B2 is likely to be attributed to higher surface recombination from organic deposits from a paper division sheet during transport. As shown in the figures in Section 3.4, this feature disappeared after treatment with Piranha solution prior to heat treatment.…”

Section: Oxygen Measurementsmentioning

confidence: 99%

The Effect of Pull Speed and Heat Treatment on Thermal Donors in Czhocralski Silicon

Olsen

Mehl

Stalheim

et al. 2021

Physica Status Solidi (a)

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In silicon crystals manufactured by the Czochralski method, oxygen is incorporated as a contaminant originating primarily from dissolution of the quartz crucible used to contain the molten silicon feedstock. The oxygen can be found either as interstitials, agglomerates, or as oxide particles. Particular kinds of agglomerates are known to lead to the formation of thermal donors—electronic states in the bandgap of the silicon base material. These can act as sites for recombination of excited charge carriers and are called thermal donors due to their ability to inject two electrons into the conduction band of silicon by thermal excitation, leading to enhanced electrical conductivity. Neither of these features are desirable in Cz‐Si manufacture. Herein, the behavior of thermal donors as a function of the pull speed, and the position in the ingot, is investigated. Thermal treatment is provided, first for the formation of thermal donors and then for their removal. The aim is to investigate methods for minimalizing their incorporation in the crystal in the first place and then how they can be removed. Hyperspectral imaging and spectroscopy combined with Fourier‐transform infrared spectroscopy are used.

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“…The advantages of the proposed method are now demonstrated using a diffused n-type Cz silicon wafer with a resistivity of 2.4 Ω cm and a The wafer is partially affected by striations (ring defect), 34,35 resulting in a spatially non-uniform lifetime distribution.…”

Section: Application To a Diffused Samplementioning

confidence: 99%

Advanced photoluminescence imaging using non‐uniform excitation

Nie

Zhu

Kunz

et al. 2021

Progress in Photovoltaics

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Photoluminescence (PL) imaging is a powerful inspection technique for research laboratories and photovoltaic production lines. Common PL imaging systems have two limitations: (a) due to the non-uniformities of the measured samples, the acquired images are affected by lateral carrier flow, resulting in inaccurate lifetime analysis and image blurring; (b) samples' non-uniformities are measured at locally different injection levels. In this paper, we present a PL imaging system that is not affected by these effects. By adaptively adjusting the light intensity at each pixel, we achieve a uniform excess carrier density across the sample, thereby eliminating any lateral currents. The non-uniformity of the minority carrier lifetime can then be extracted from the spatial inverse of the illumination intensity. The advantages of the proposed system are demonstrated using silicon wafers with and without a diffusion layer that contain non-uniform defects. This approach presents a significant improvement in accuracy and sharpness compared to conventional PL imaging techniques and, therefore, is expected to be beneficial for any quantitative PL-based analysis.

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Removing the effect of striations in n-type silicon solar cells

Cited by 36 publications

References 17 publications

Hydrogen induced degradation: A possible mechanism for light- and elevated temperature- induced degradation in n-type silicon

Hydrogen induced degradation: A possible mechanism for light- and elevated temperature- induced degradation in n-type silicon

The Effect of Pull Speed and Heat Treatment on Thermal Donors in Czhocralski Silicon

Advanced photoluminescence imaging using non‐uniform excitation

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