Measurement of local recombination activity in high diffusion length semiconductors

Heinz, Friedemann D.; Oezkent, Maximilian; Rittmann, Clara; Schindler, Florian; Schubert, Martin C.; Kwapil, Wolfram; Glunz, Stefan

doi:10.1016/j.solmat.2023.112477

Cited by 4 publications

(1 citation statement)

References 26 publications

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“…Further details of the simulation setup for ELBA can be found in the work by Richter et al [20] To achieve higher spatial resolution in capturing recombination activity, micro-photoluminescence (μPL) measurements were performed. [24] The μPL setup utilized a confocal microscope for localized excitation of minority charge carriers and localized detection of the emitted PL signal. Scanning the entire EpiWafer with the confocal microscope generates a μPL intensity map.…”

Section: Characterization Methodsmentioning

confidence: 99%

Toward Highly Efficient Low‐Carbon Footprint Solar Cells: Impact of High‐Temperature Processing on Epitaxially Grown p‐Type Silicon Wafers

Rittmann,

Messmer,

Niewelt

et al. 2024

Solar RRL

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Conventional silicon (Si) wafers are produced by energy‐intensive ingot crystallization which is responsible for a major share of a solar cell’s carbon footprint. Our work explores Si EpiWafers that are produced by direct epitaxial deposition of trichlorosilane on a re‐usable substrate. This approach requires less energy and material and hence offers a potential for reduced cost and carbon footprint. Solar cells made from EpiWafers usually suffer from efficiency losses due to recombination at structural crystal defects associated with epitaxial growth. We investigated the nature of these defects and observed that defects at the EpiWafer’s back surface are critical. Most of these defects are highly recombination‐active, pairwise‐connected misfit dislocations in the <110>‐direction. They originate from a lattice mismatch between the highly‐doped substrate and the less‐doped epitaxially grown layer. In this contribution, we demonstrate that the detrimental impact of these defects can be mitigated using typical manufacturing processes of high‐efficiency solar cells, such as KOH‐etching, gettering and oxidation. We report local minority charge carrier lifetimes as high as 2.2 ms after industrially feasible processes. Simulations using efficiency limiting bulk recombination analysis (ELBA) imply that the material would allow conversion efficiencies of up to 25.6 % considering a TOPCoRE solar cell design.TOC: Epitaxially grown silicon wafers (EpiWafers) are a promising alternative to Cz‐Si wafers for highly efficient solar cells with a low carbon footprint. For p‐type EpiWafers, we report minority charge carrier lifetimes as high as 2.2 ms and an efficiency potential of 25.6 %. Structural defects, as a remaining quality limitation in the EpiWafer, are discussed with respect to the effect of KOH‐etching, gettering, and oxidation.This article is protected by copyright. All rights reserved.

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Section: Characterization Methodsmentioning

confidence: 99%

Toward Highly Efficient Low‐Carbon Footprint Solar Cells: Impact of High‐Temperature Processing on Epitaxially Grown p‐Type Silicon Wafers

Rittmann,

Messmer,

Niewelt

et al. 2024

Solar RRL

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Recombination Activity of Crystal Defects in Epitaxially Grown Silicon Wafers for Highly Efficient Solar Cells

Rittmann,

Supik,

Drießen

et al. 2024

Physica Status Solidi (a)

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Aiming for highly efficient solar cells based on wafers with a low carbon footprint, silicon (Si) EpiWafers are grown epitaxially on reusable, highly doped Si substrates with a stack of porous Si layers (PorSi) for detachment. A state‐of‐the‐art p‐type Si EpiWafer exhibiting a minority charge carrier lifetime of up to 2.2 ms detected at an excess charge carrier density of ≈1 × 1015 cm−3 by photoluminescence (PL) imaging is presented. This translates to a predicted solar cell efficiency of 25.6%, calculated by efficiency limiting bulk recombination analysis (ELBA), and corresponds to losses of less than 1%abs compared to the theoretical limit of the investigated solar cell concept. A detailed loss analysis shows that the major remaining quality limitations are structural defects, specifically stacking faults (SFs). Therefore, the recombination activity of isolated SFs in epitaxially grown reference (EpiRef) wafers on polished substrates without a PorSi is assessed by highly resolved μPL mappings. The recombination activity rises with the number of dislocations within an SF as demonstrated by a comparison to microscope images. When using highly doped substrates, as currently required for EpiWafer fabrication, EpiRef wafers show more SFs exhibiting additionally a higher number of dislocations than SFs in EpiRef wafers on moderately doped substrates.

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Synergizing nanotechnology, codoping, and reinforcement with rGO to increase the catalytic activity of a modified Ho/Cr-FeNdO3-rGO nanocomposite for tartrazine removal

Al Alwan,

Aadil,

Khalid

et al. 2024

Ceramics International

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Measurement of local recombination activity in high diffusion length semiconductors

Cited by 4 publications

References 26 publications

Toward Highly Efficient Low‐Carbon Footprint Solar Cells: Impact of High‐Temperature Processing on Epitaxially Grown p‐Type Silicon Wafers

Toward Highly Efficient Low‐Carbon Footprint Solar Cells: Impact of High‐Temperature Processing on Epitaxially Grown p‐Type Silicon Wafers

Recombination Activity of Crystal Defects in Epitaxially Grown Silicon Wafers for Highly Efficient Solar Cells

Synergizing nanotechnology, codoping, and reinforcement with rGO to increase the catalytic activity of a modified Ho/Cr-FeNdO3-rGO nanocomposite for tartrazine removal

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