Passivating electron contact based on highly crystalline nanostructured silicon oxide layers for silicon solar cells

Stückelberger, Josua; Nogay, Gizem; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Debrot, F.; Niquille, X.; Ledinský, Martin; Fejfar, A.; Despeisse, M.; Haug, Franz‐Josef; Löper, P.; Ballif, Christophe

doi:10.1016/j.solmat.2016.06.040

Cited by 91 publications

(60 citation statements)

References 26 publications

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“…Alternatively, a stack of an ultrathin SiO x layer and hydrogenated nanocrystalline silicon carbide (nc-SiC x :H) can provide excellent surface passivation after postdeposition annealing at high temperatures without using an a-Si:H interlayer [74]. This contact stack can be used to form a hole-selective passivating contact, as is illustrated by excellent values of both J 0 (9 fA/cm 2 on n-type Si; 11 fA/cm 2 on p-type Si) and ρ contact (86 mΩ•cm 2 on n-type Si; 19 mΩ•cm 2 on p-type Si) [78]. Its material and contact properties are comparable with the previously discussed SiO x /poly-Si structure, and it is compatible with high-temperature metallization schemes.…”

Section: A Si-based Materialsmentioning

confidence: 98%

Passivating Contacts for Crystalline Silicon Solar Cells: From Concepts and Materials to Prospects

Melskens

Loo

Macco

et al. 2018

IEEE J. Photovoltaics

302

254

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Section: A Si-based Materialsmentioning

confidence: 98%

Passivating Contacts for Crystalline Silicon Solar Cells: From Concepts and Materials to Prospects

Melskens

Loo

Macco

et al. 2018

IEEE J. Photovoltaics

302

254

View full text Add to dashboard Cite

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“…Because of the importance of the dopant diffusion, it is also necessary to evaluate the nature of the polycrystalline on textured n-type Si wafers, especially at the front (p) poly-Si/SiO x stack that was reported to have a weaker passivation property than (n) poly-Si/SiO x stack. 9,17,18,22,[51][52][53][54][55][56][57] The polycrystalline nature of the boron doped (p) poly-Si layer is analyzed by nanobeam diffraction pattern on HR-TEM ( Figure 4). The well poly-crystallized (p) poly-Si nature, with clear atomic plans and amorphous parts, is observed regardless of the surface and orientation, even at the bottom of a valley and the top of a tip on textured surface (Figure 4).…”

Section: Poly-si and Sio X Layersmentioning

confidence: 99%

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Lozac’h

Nunomura

2020

Progress in Photovoltaics

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We investigate the role of the silicon surface and orientation on double‐sided TOPCon solar cells properties. The solar cells of front and rear, (p) and (n), poly‐Si/SiOx stack, fabricated on polished surfaces oriented 〈100〉 and 〈111〉 and pyramid textured surfaces, are characterized as a function of the thickness of an ultrathin SiOx layer, controlled at atomic scale from one‐ to four‐cycle atomic layer deposition (ALD). Our findings underline that the optimized thickness of the ultrathin SiOx is about 1.1 ± 0.1 nm, corresponding to a two‐cycle ALD, regardless of the surface and orientation of the c‐Si substrate. The open‐circuit voltage is about 10 mV higher on the polished 〈100〉‐oriented surface, associated with lower defect density at the interface of SiOx/c‐Si. On the other hand, the contact resistance is much lower, about 0.45 Ω/cm2, on the polished 〈111〉‐oriented surface. On textured surfaces, we demonstrate a photoconversion efficiency of 19.1% for the double‐sided TOPCon structure strictly for a SiOx thickness with two‐cycle ALD, which underlines the importance of the ALD technique for the precise control of the ultrathin SiOx thickness on textured surface.

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“…The POLO contacts consist of a thin interfacial oxide under a doped poly-Si layer, onto which the metal contacts are applied. They enable both, low contact resistances as well as a good passivation quality of the c-Si surface below the metal contacts [13][14][15][16][17] , thus enhancing the contact selectivity strongly as compared to conventional diffused junctions 18,19 .…”

mentioning

confidence: 99%

Separating the two polarities of the POLO contacts of an 26.1%-efficient IBC solar cell

Hollemann

Haase

Rienäcker

et al. 2020

Sci Rep

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This is because the high conductivity of the poly-Si does not impede a transport limitation. Therefore, a separation of the n-type POLO (nPOLO) and p-type POLO (pPOLO) contact fingers is required [25][26][27][28][29] .In this work we employ a POLO junction scheme that consists of an initially full area intrinsic poly-Si (i poly-Si) layer that is locally doped by ion implantation. From process leanness point of view an attractive option to avoid these pn junctions in the poly-Si is to leave an (i) poly-Si region between emitter and base fingers. This is expected to result in lateral p(i)n poly-Si junction at the rear side of the IBC cell, which is connected in parallel to the nPOLO/p-type c-Si junctions ( Fig. 1a). By applying the described junction scheme we demonstrated a solar cell with an efficiency of 26.1% 11,21 .This concept was previously tested by other groups on precursor level 30 achieving a V OC of 682 mV with an pFF of 80% and on the cell level 27 yielding an efficiency of 18.4%. Both devices showed high ideality factors pointing to a non-ideal recombination in the space charge region. To evaluate why our cell, in contrast, does not suffer from a high ideality factor we perform a systematic study of the device physics of the resulting p(i)n poly-Si diodes.We quantify the defect density in our poly-Si layers prior and after hydrogenation using time-dependent photoluminescence decay measurements in the picosecond regime.As the purpose of the (i) poly-Si regions is to suppress high recombination currents across the p(i)n diode a large (i) poly-Si region is desirable. On the other hand, we observed a poor passivation quality of the c-Si absorber by the iPOLO on full-area lifetime test structures (see below). This is due to the moderate chemical passivation of SiO x on p-type Si, which further degrades when forming the nanometer-sized pinholes in the interfacial oxide 31 . This reasoning favors small (i) poly-Si widths. To find an optimum between these counteracting requirements, we experimentally vary the width of the (i) poly-Si region from nominal d gap = 0 µm up to 380 µm.We experimentally find that a width of the initially i poly-Si layer of d gap = 30 µm together with a high annealing temperature of over 1000 °C enables a record cell efficiency of 26.1%. From measurements on full area test structures and numerical device simulations we know that the surface recombination velocity at the intrinsic poly-Si is above 2000 cm/s and would limit the device efficiency to 15%. We conclude that the nominally intrinsic poly-Si layer is no longer intrinsic after the full cell process.We therefore investigate an inter-diffusion of dopants from the n-type and p-type doped fingers into the initially intrinsic poly-Si region by a lateral Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) measurement. Combining all three aspects, we are, for the first time, able to present a comprehensive understanding of the working principle of high-efficient POLO IBC cells with p(i)n poly-Si diodes. Scientific RepoRtS |(202...

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Passivating electron contact based on highly crystalline nanostructured silicon oxide layers for silicon solar cells

Cited by 91 publications

References 26 publications

Passivating Contacts for Crystalline Silicon Solar Cells: From Concepts and Materials to Prospects

Passivating Contacts for Crystalline Silicon Solar Cells: From Concepts and Materials to Prospects

Role of silicon surface, polished 〈100〉 and 〈111〉 or textured, on the efficiency of double‐sided TOPCon solar cells

Separating the two polarities of the POLO contacts of an 26.1%-efficient IBC solar cell

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