Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story?

Peibst, Robby; Römer, Udo; Larionova, Yevgeniya; Rienäcker, Michael; Merkle, Agnes; Folchert, Nils; Reiter, Sina; Turcu, M.; Min, Byungsul; Krügener, Jan; Tetzlaff, D.; Bugiel, E.; Wietler, Tobias; Brendel, Rolf

doi:10.1016/j.solmat.2016.05.045

Cited by 191 publications

(167 citation statements)

References 20 publications

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“…For a wafer thickness of 165 μm, the estimated practical limit for i V oc is 748 mV according to Yoshikawa et al To achieve such values close to the practical limit, Taguchi et al claim that an ultraclean surface is needed, which was not assured for the sample preparation of this work as the HWCVD growth of μc‐SiC:H(n) was not performed in a clean room. Compared with TOPCon/POLO technology, the J 0 values of μc‐SiC:H(n)/SiO 2 passivation are among the lowest J 0 values reported in the recent past for wet‐chemically grown oxides ranging from 1.5 to 20 fA/cm 2 . The improvement in μc‐SiC:H(n)/SiO 2 passivation as compared with our former work was achieved by a convolution of an improved surface texture of the c‐Si wafer, higher c‐Si bulk lifetime, and optimized HWCVD process for the μc‐SiC:H(n) deposition.…”

Section: Discussionsupporting

confidence: 67%

Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

Pomaska

Köhler

Procel

et al. 2020

Progress in Photovoltaics

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N‐type microcrystalline silicon carbide (μc‐SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c‐Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc‐SiC:H(n) for c‐Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc‐SiC:H(n) on tunnel oxide (SiO2)–passivated c‐Si with an implied open‐circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm2. This excellent passivation quality is achieved directly after the HWCVD deposition of μc‐SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF2)/silicon nitride (SiNx:H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm2 with MgF2/SiNx:H/μc‐SiC:H(n) and 0.62 mA/cm2 with MgF2/μc‐SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF2/μc‐SiC:H(n)/SiO2/c‐Si as front side layer stack in an IBC solar cell reveal a short‐circuit current density of 42.2 mA/cm2, an open‐circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%.

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Section: Discussionsupporting

confidence: 67%

Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

Pomaska

Köhler

Procel

et al. 2020

Progress in Photovoltaics

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“…Therefore, a high annealing temperature would be beneficial for a low interface state density D it . There is theoretical and experimental support of the picture that the interfacial oxide breaks up locally . This local break‐up does not compromise the POLO junction passivation quality as long as the pinhole size is only a few nanometers, and the pinhole areal density is in the range of ∼10 7 cm −2 .…”

Section: Experimental Results On Planar and Textured Surfacesmentioning

confidence: 88%

“…One should note that this analysis disregards a laterally inhomogeneous passivation due to pinhole formation. However, this approximation is justified for pinhole areal densities <10 7 cm −2 , where recombination is dominated by the regions where the interfacial oxide is still intact . For a doping concentration of N A = 2 × 10 18 cm −3 at the c‐Si/SiO x interface, we obtained S n,0 values of 220 cm s −1 for the (100) surface orientation and of 2400 cm s −1 for the (111) surface orientation (right axis of Fig.…”

Section: Experimental Results On Planar and Textured Surfacesmentioning

confidence: 90%

“…There is theoretical and experimental support of the picture that the interfacial oxide breaks up locally . This local break‐up does not compromise the POLO junction passivation quality as long as the pinhole size is only a few nanometers, and the pinhole areal density is in the range of ∼10 7 cm −2 . However, for excessive thermal budgets, the pinhole areal density and size further increase until the “too intensive break‐up,” which implies a strong degradation in passivation quality .…”

Section: Experimental Results On Planar and Textured Surfacesmentioning

confidence: 96%

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On the recombination behavior of p⁺-type polysilicon on oxide junctions deposited by different methods on textured and planar surfaces

Larionova

Turcu

Reiter

et al. 2017

Phys. Status Solidi A

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We investigate the passivation quality of hole‐collecting junctions consisting of thermally or wet‐chemically grown interfacial oxides, sandwiched between a monocrystalline‐Si substrate and a p‐type polycrystalline‐silicon (Si) layer. The three different approaches for polycrystalline‐Si preparation are compared: the plasma‐enhanced chemical vapor deposition (PECVD) of in situ p+‐type boron‐doped amorphous Si layers, the low pressure chemical vapor deposition (LPCVD) of in situ p+‐type B‐doped polycrystalline Si layers, and the LPCVD of intrinsic amorphous Si, subsequently ion‐implanted with boron. We observe the lowest J0e values of 3.8 fA cm−2 on thermally grown interfacial oxide on planar surfaces for the case of intrinsic amorphous Si deposited by LPCVD and subsequently implanted with boron. Also, we obtain a similar high passivation of p+‐type poly‐Si junctions on wet‐chemically grown oxides as well as for all the investigated polycrystalline‐Si deposition approaches. Conversely, on alkaline‐textured surfaces, J0e is at least 4 times higher compared to planar surfaces. This finding holds for all the junction preparation methods investigated. We show that the higher J0e on textured surfaces can be attributed to a poorer passivation of the p+ poly/c‐Si stacks on (111) when compared to (100) surfaces.

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“…Several studies have shown that increasing T a degraded the SiO x film [9][10][11][12]. However, in certain cases the SiO x degradation has been shown to be beneficial, leading to nanoscale pinholes within the SiO x film which improve the transport of free charge carriers through the SiO x film [13,14]. …”

Section: Increase Of the Annealing Temperaturementioning

confidence: 99%

Improvement of the conductivity and surface passivation properties of boron-doped poly-silicon on oxide

Morisset¹,

Cabal²,

Grange³

et al. 2018

AIP Conference Proceedings

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Abstract. Passivating contacts of crystalline silicon (c-Si) solar cells with a poly-silicon layer (poly-Si) on a thin silicon oxide (SiOx) film offer an interesting approach to decrease the recombination current at the metal/c-Si interface and to increase the cell efficiency. This study focuses on the development of boron-doped poly-Si layers deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD) on top of a thin silicon oxide film. First, the deposition and annealing conditions were optimised in order to: (1) reduce the blistering of the poly-Si on the thin SiOx film and (2) improve the poly-Si conductivity. The passivation properties of the resulting structures have been shown to depend on the blister density and have been improved through a hydrogenation step leading to a maximum implied open-circuit voltage value of 721 mV.

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Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story?

Cited by 191 publications

References 20 publications

Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

On the recombination behavior of p⁺-type polysilicon on oxide junctions deposited by different methods on textured and planar surfaces

Improvement of the conductivity and surface passivation properties of boron-doped poly-silicon on oxide

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Working principle of carrier selective poly-Si/c-Si junctions: Is tunnelling the whole story?

Cited by 191 publications

References 20 publications

Transparent silicon carbide/tunnel SiO2 passivation for c‐Si solar cell front side: Enabling Jsc > 42 mA/cm2 and iVoc of 742 mV

Transparent silicon carbide/tunnel SiO2 passivation for c‐Si solar cell front side: Enabling Jsc > 42 mA/cm2 and iVoc of 742 mV

On the recombination behavior of p+-type polysilicon on oxide junctions deposited by different methods on textured and planar surfaces

Improvement of the conductivity and surface passivation properties of boron-doped poly-silicon on oxide

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Product

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Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

Transparent silicon carbide/tunnel SiO₂ passivation for c‐Si solar cell front side: Enabling J_sc > 42 mA/cm² and iV_oc of 742 mV

On the recombination behavior of p⁺-type polysilicon on oxide junctions deposited by different methods on textured and planar surfaces