Implementation and understanding of p+ fired rear hole selective tunnel oxide passivating contacts enabling &gt;22% conversion efficiency in p-type c-Si solar cells

Ingenito, Andrea; Libraro, Sofia; Wyss, Philippe; Allebé, Christophe; Despeisse, Matthieu; Nicolay, Sylvain; Haug, Franz‐Josef; Ballif, Christophe

doi:10.1016/j.solmat.2020.110809

Cited by 15 publications

(6 citation statements)

References 29 publications

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“…Overall, J 0,pass is in the range of 10−20 fA cm − 2 , which is just at the edge of being acceptable for the investigation presented later, but considerably larger than values achieved in the past, where, typically, J 0,pass < 4fA cm −2 has been reached, [ 24 ] and similar values have been reported also by other authors. [ 15,22 ] At this point, the reason for the rather high recombination current densities is unclear. There is a tendency toward lower J 0,pass for higher firing set temperatures T set , in accordance with earlier results.…”

Section: Resultsmentioning

confidence: 99%

“…[ 16 ] However, the actual demonstration of a solar cell with screen‐printed metallization that comes near the determined efficiencies in simulation can be challenging, for the reasons explained earlier, resulting only in a limited amount of publications. [ 17,18 ] Alternatively, in other contributions, physical vapor deposition (PVD) is used often for rear metallization [ 19–22 ] due to the noninvasiveness of this technology. As laser damage from local ablation of dielectric capping layers can be kept to a minimum if the polysilicon layer does not go below a certain thickness, [ 21 ] the TOPCon interface properties should ideally not be affected by metallization.…”

Section: Introductionmentioning

confidence: 99%

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Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

et al. 2021

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Herein, an update on the work on high‐efficiency p‐type solar cells with p‐type‐passivating rear contacts formed by low‐pressure chemical vapor deposition and screen‐printed contacts is given. It is shown that thin polysilicon layers enable a high level of surface passivation but do show increased contact resistivity and especially contact recombination. Commercially available pastes and dependence of contact resistivity and contact recombination on polylayer thickness and firing set temperature are investigated. For 240 nm‐thick poly‐Si layers, the values down to 4 mΩ cm2 and 60 fA cm−2 are observed. For the presented process sequence, improved hydrogenation as one possibility to increase the passivation quality of the passivating contact structure is identified. Implementing all findings into a final solar cell, a maximum total area conversion efficiency of 21.2% is reported.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

et al. 2021

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“…However, the fired passivating contact (FPC) approach simplifies the process flow. Thereby, the thermal budget is significantly reduced, ideally featuring only one fast firing step, which combines metallization, dopant activation, partial crystallization, and hydrogenation [3]. A good passivation quality was already shown previously for plasma-enhanced chemical vapor deposition (PECVD) as well as atmospheric pressure chemical vapor deposition (APCVD) a-Si [3], [4], [5].…”

Section: Introductionmentioning

confidence: 87%

“…Thereby, the thermal budget is significantly reduced, ideally featuring only one fast firing step, which combines metallization, dopant activation, partial crystallization, and hydrogenation [3]. A good passivation quality was already shown previously for plasma-enhanced chemical vapor deposition (PECVD) as well as atmospheric pressure chemical vapor deposition (APCVD) a-Si [3], [4], [5]. In contrary to PECVD, APCVD enables a high throughput and completely blister-free poly-Si without any additional steps, such as annealing before SiNX:H deposition [3].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Contact Resistivities on APCVD (p) Poly-Si for Fired Passivating Contacts

Okker,

Glatthaar,

Huster

et al. 2024

SiliconPV Conf Proc

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We investigate the properties of boron doped polycrystalline Si (poly-Si) deposited by atmospheric pressure chemical vapor deposition (APCVD) applied to fired passivating contacts (FPC), where no high temperature annealing takes place apart from the contact firing step. X-ray diffraction measurements show that the APCVD poly-Si is already partially crystallized directly after deposition and the crystallite size further increases during firing. Without metallization an implied open circuit voltage of up to 719 mV is achieved. Screen-printing with an Ag paste yields minimal contact resistivities of down to 1 mΩcm² at high firing temperatures. Furthermore, thicker poly-Si layers, accomplished by driving the same wafer multiple times through the APCVD system, generally correspond to lower contact resistivities for the FPC. This can partly be explained by an increasing crystallinity and conductivity during deposition due to the higher thermal budget during deposition for thicker layers as well as by a larger contact area for thicker poly-Si layers. Scanning electron microscopy on sample cross-sections show that almost the entire poly-Si layer is covered with Ag crystallites at high firing temperatures. For lower temperatures a lower density of Ag crystallites in the poly-Si is visible. Both findings hold for planar and textured surfaces.

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“…In the present work, we investigate the possibility to use a simplified process flow for the fabrication of FPC samples, in a way close to the one proposed by Ingenito et al [ 10 ] As shown in Figure 1b and detailed in a previous communication, it consists in depositing sequentially a stack of silicon oxide (SiO x )/(p) nanocrystalline silicon (nc‐Si:H)/a‐SiN x :H and making a final firing step. [ 7 ] The tunnel SiO x layer provides chemical passivation to the surface of the wafer while allowing the transport of charge carriers by diffusion through pinholes or tunneling; the doped nc‐Si:H layer has the role of a carrier‐selective contact (conductivity, band bending).…”

Section: Introductionmentioning

confidence: 99%

In situ modulated photoluminescence study of the hydrogenation processes of tunnel oxide passivating contacts during plasma processes

Desthieux

Gaillard

Posada

et al. 2022

Plasma Processes & Polymers

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Compared to current c-Si solar cell technologies, fired passivating contacts (FPCs) can reduce the thermal budget of the solar cell fabrication process. In this study, a simplified process flow for the fabrication of these contacts is investigated along with the use of two hole transport materials: p-type nanocrystalline silicon ((p) nc-Si:H) and nanocrystalline silicon oxide ((p) nc-SiO x :H). More specifically, the passivation properties provided by the FPC stack are assessed at different stages of the manufacturing. The hydrogenation process is studied using in situ modulated photoluminescence (MPL) which allows to measure in real time the effective minority carrier lifetime in the sample during a process step. The increase of passivation observed during the deposition of the capping silicon-nitride (a-SiN x :H) layer by plasma-enhanced chemical vapor deposition is shown to be due to both annealing of the sample and the deposition in presence of silane in the plasma, while the exposure to an NH 3 and H 2 plasma is mostly detrimental for the passivation properties. The in situ MPL measurements additionally allow us to show that the improvement of the passivation properties happens during the first few minutes of a-SiN x :H deposition.

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Implementation and understanding of p+ fired rear hole selective tunnel oxide passivating contacts enabling >22% conversion efficiency in p-type c-Si solar cells

Cited by 15 publications

References 29 publications

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

Progress in p‐type Tunnel Oxide‐Passivated Contact Solar Cells with Screen‐Printed Contacts

Investigation of Contact Resistivities on APCVD (p) Poly-Si for Fired Passivating Contacts

In situ modulated photoluminescence study of the hydrogenation processes of tunnel oxide passivating contacts during plasma processes

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