Studying dopant diffusion from Poly-Si passivating contacts

Feldmann, Frank; Schön, Jonas; Niess, Jürgen; Lerch, W.; Hermle, Martin

doi:10.1016/j.solmat.2019.109978

Cited by 61 publications

(34 citation statements)

References 34 publications

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“…The doping profile in the poly-Si layer and at the surface of the c-Si substrate is known to play a role in the final surface passivation properties of the poly-Si/SiOx contact [17,32].…”

Section: Variation Of the Doping Profile With Increasing Annealing Temperaturementioning

confidence: 99%

Evolution of the surface passivation mechanism during the fabrication of ex-situ doped poly-Si(B)/SiOx passivating contacts for high-efficiency c-Si solar cells

Morisset

Cabal

Giglia

et al. 2021

Solar Energy Materials and Solar Cells

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Passivating the contacts of crystalline silicon (c-Si) solar cells (SC) with a poly-crystalline silicon (poly-Si) layer on top of a thin silicon oxide (SiOx) is currently sparking interest for reducing carrier recombination at the interface between the metal electrode and the c-Si substrate. However, due to the interrelation between different mechanisms at play, a comprehensive understanding of the surface passivation provided by the poly-Si/SiOx contact in the final SC has not been achieved yet. In the present work, we report on an original ex-situ doping process of the poly-Si layer through the deposition of a B-rich dielectric layer followed by an annealing step to diffuse B dopants in the layer. We propose an in-depth investigation of the passivation scheme of the resulting B-doped poly-Si/SiOx contact by first comparing the surface passivation provided by ex-situ doped and intrinsic poly-Si/SiOx contacts at different steps of the fabrication process. The excellent surface passivation properties obtained with the ex-situ doped poly-Si(B) contact (iVoc = 733 mV and J0 = 6.1 fA cm -2 ) attests to the good quality of this contact. We then propose further STEM, ECV and ToF-SIMS characterizations to assess: i) the evolution of the microstructure and

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“…The doping profile in the poly-Si layer and at the surface of the c-Si substrate is known to play a role in the final surface passivation properties of the poly-Si/SiOx contact [17,32].…”

Section: Variation Of the Doping Profile With Increasing Annealing Temperaturementioning

confidence: 99%

Evolution of the surface passivation mechanism during the fabrication of ex-situ doped poly-Si(B)/SiOx passivating contacts for high-efficiency c-Si solar cells

Morisset

Cabal

Giglia

et al. 2021

Solar Energy Materials and Solar Cells

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“…Prominent is the peak at the position of the thermally grown SiO x at the poly-Si/c-Si interface. It is known that SiO x is a diffusion barrier for P and that P piles up at such oxides [19], [20], which was also previously observed for TOPCon structures [18], [21]. However, quantitative analysis of the peak at the poly-Si/SiO x interface is difficult due to the so-called SIMS matrix effect, which describes the enhancement of ion yield resulting from the presence of oxygen or cesium [22], [23].…”

Section: A Standard P/n Sitjmentioning

confidence: 81%

“…The diffusion of P into the absorber at the poly-Si(n + )/SiO x /c-Si(n) interface, which supports the surface passivation [18], was defined by the FA and hardly changed by the RTP. Within c-Si, the P profiles were very similar independent of T RTP .…”

Section: A Standard P/n Sitjmentioning

confidence: 84%

Controlling Diffusion in Poly-Si Tunneling Junctions for Monolithic Perovskite/Silicon Tandem Solar Cells

Luderer

Penn

Reichel

et al. 2021

IEEE J. Photovoltaics

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The performance of a low-resistive p + /n + poly-Si tunneling junction (SiTJ) based on a tunnel oxide passivating contact in dependence on the thermal budget of the applied post-deposition treatment is studied. We present two approaches to reduce the performance limiting parasitic dopant interdiffusion and, thus, the contact resistivity, without impairing the passivation quality. Both, carbon-alloying of poly-Si layers and the application of diffusion blocking interlayers are effective means to maintain a low contact resistivity of ∼24 mΩcm 2 at high thermal process temperatures of up to 950°C. Those low values are obtained using either a standard furnace anneal or a rapid thermal process (RTP). We report on promising results toward a lean process sequence using only one single fast thermal treatment (RTP-only). As a main result, the flexibility for engineering and fabrication of our SiTJ was markedly improved, eventually facilitating industrially feasible perovskite/silicon tandem solar cells. One aspect being higher post-deposition temperatures needed for, e.g., bottom cell rear side contact formation and the first layers of the perovskite to cell.

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“…For passivating contacts based on poly-Si alloy, the doping level within the poly-Si alloy layer and the doping profile across the poly-Si alloy/SiO x /c-Si interface are the main factors influencing the quality of the field-effect passivation. 53 There are some parameters that can control the doping level and profile for such PECVD prepared passivating contacts: (i) the phosphorus or boron content in the PECVD a-SiO x :H layers, (ii) the thicknesses of the intrinsic and doped PECVD a-SiO x :H layers, (iii) the thermal budget of high-temperature annealing process, and (iv) the thickness and quality of the ultrathin SiO x layers.…”

Section: Influence Of Doping Ratiomentioning

confidence: 99%

Oxygen‐alloyed poly‐Si passivating contacts for high‐thermal budget c‐Si heterojunction solar cells

Yang

Han

Procel

et al. 2021

Progress in Photovoltaics

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Crystalline silicon solar cells with passivating contacts based on doped poly-Si exhibit high optical parasitic losses. Aiming at minimizing these losses, we developed the oxygen-alloyed poly-Si (poly-SiO x ) as suitable material for passivating contacts. From passivation point of view, poly-SiO x layers show excellent passivation quality and carrier selectivity for both n-type (iV OC,flat = 740 mV, contact resistance ρ c = 0.7 mΩ/cm 2 , iV OC,textured = 723 mV) and p-type (iV OC,flat = 709 mV, ρ c = 0.5 mΩ/cm 2 ). Optically, due to the incorporation of oxygen, the absorption coefficient of poly-SiO x becomes much lower than that of doped poly-Si at long wavelength. Both n-type and p-type poly-SiO x layers are concurrently deployed in front/back-contacted (FBC) solar cells with a front indium tin oxide (ITO) layer to

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Studying dopant diffusion from Poly-Si passivating contacts

Cited by 61 publications

References 34 publications

Evolution of the surface passivation mechanism during the fabrication of ex-situ doped poly-Si(B)/SiOx passivating contacts for high-efficiency c-Si solar cells

Evolution of the surface passivation mechanism during the fabrication of ex-situ doped poly-Si(B)/SiOx passivating contacts for high-efficiency c-Si solar cells

Controlling Diffusion in Poly-Si Tunneling Junctions for Monolithic Perovskite/Silicon Tandem Solar Cells

Oxygen‐alloyed poly‐Si passivating contacts for high‐thermal budget c‐Si heterojunction solar cells

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