Electronic interface properties of silicon substrates after ozone based wet-chemical oxidation studied by SPV measurements

Wolke, K.; Gottschalk, Christiane; Moldovan, Ana; Roczen, Maurizio; Fittkau, Jens; Zimmer, Martin; Rentsch, J.

doi:10.1016/j.apsusc.2012.03.170

Cited by 20 publications

(9 citation statements)

References 25 publications

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“…Thickness gap, similar to the observation by Angermann et al [55] who observed a skewing toward the conduction band when p-type Si substrates are utilized. As compared to other thermally grown silicon oxides [56][57][58][59] which exhibited significantly lower D it values ($1-2 orders), their film thickness was however also significantly higher at $50-240 nm, making it inappropriate for tunnel layer applications.…”

Section: Tunnel Oxidesupporting

confidence: 85%

“…On the other hand, the wet-SiO x and ozone-SiO x tunnel oxides reported in Refs. [55,57,[60][61][62][63][64] do exhibit measurable Q f and D it values, unlike our investigated samples, which can be attributed to the deposition method and the postdeposition annealing conditions. Our wet-SiO x and ozone-SiO x tunnel oxides were unable to retain the deposited corona charges due to its leaky interface, which nonetheless could be beneficial for the purpose of tunneling carrier transport.…”

Section: Tunnel Oxidecontrasting

confidence: 56%

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Double-Sided Passivated Contacts for Solar Cell Applications: An Industrially Viable Approach Toward 24% Efficient Large Area Silicon Solar Cells

Ling¹,

Zhang²,

Wang³

et al. 2019

Silicon Materials

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Tunnel layer passivated contacts have been successfully demonstrated for next-generation silicon solar cell concepts, achieving improved device performance stemming from the significantly reduced contact recombination of the solar cell contacts. However, these carrier-selective passivated contacts are currently deployed only at the rear side of the silicon solar cell, while the front side adopts a conventional diffused junction and contacting scheme. In this work, we report on the novelty and feasibility of deploying tunnel layer passivated contacts on both sides of a silicon wafer-based solar cell, featuring a textured front surface and a planar rear surface. In particular, we demonstrate that silicon solar cells incorporating our in-house developed electron-selective thermal-SiO x /poly-Si(n +) and hole-selective thermal-SiO x /poly-Si(p +) passivated contacts have a solar cell efficiency potential approaching 24%. Deploying contact passivation only at the rear side of the solar cell, we have reached a solar cell efficiency of 21.7%, using conventional screen printing for metallization. We present a systematic approach of evaluating our in-house developed electron-selective and hole-selective passivated contacts on both textured and planar lifetime test structures, as well as dark I-V test structures, to extract the recombination current density j 0 and the contact resistance R c of the passivated contact, which is used for process optimization as well as for subsequent efficiency potential prediction. The two key challenges aiming at a double-sided integration of passivated contacts are (1) parasitic absorption within the front-side highly doped poly-Si capping layer, requiring the processing of ultrathin (≤10-nm) contact passivation layers. This has been quantified by numerical simulation (using SunSolve™) and also solved experimentally, i.e., processing ultrathin 3-/10-nm hole/electron extracting SiO x /poly-Si(p + /n +) passivated contact layers, reaching an implied open-circuit voltage of 690/703 mV on a planar/textured silicon surface, which will even further enhance after SiN x capping. (2) Ensuring process compatibility with conventional screen printing: Screen printing on electron extracting poly-Si(n +) seems feasible; however, screen printing on holeextracting poly-Si(p +) is still a challenge. Solar cell precursors have been processed, showing excellent pre-metallization results (implied-V OC $ 713 mV). According to 1 our efficiency potential prediction (using the measured j 0 and R c values of our developed contact passivation layers), bifacial double-sided passivated contact solar cells (efficiency potential of $23.2%, using our layers) can clearly outperform rearside-only passivated contact solar cells (efficiency potential of $22.5%).

show abstract

Section: Tunnel Oxidesupporting

confidence: 85%

Section: Tunnel Oxidecontrasting

confidence: 56%

Double-Sided Passivated Contacts for Solar Cell Applications: An Industrially Viable Approach Toward 24% Efficient Large Area Silicon Solar Cells

Ling¹,

Zhang²,

Wang³

et al. 2019

Silicon Materials

View full text Add to dashboard Cite

show abstract

“…Such wide symmetrical defect distributions have up to now only been achieved by a nearly defect-free H-terminated surface or at interfaces of thicker (∼10 nm) thermal oxides [40]. Fig.…”

Section: E-e I [Ev] (A)mentioning

confidence: 99%

“…The dependence of the density of interface states (D it ) at the Si/SiO 2 interface on the silicon surface morphology and on the surface roughness prior to oxidation was investigated and modeled in references [37][38][39][40]. The electronic properties of Si/SiO 2 interfaces are governed by the density and type of interface states resulting from different types of dangling bond defects [41].…”

Section: Introductionmentioning

confidence: 99%

Improved Si/SiOx interface passivation by ultra-thin tunneling oxide layers prepared by rapid thermal oxidation

Gad

Vossing

Balamou

et al. 2015

Applied Surface Science

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“…Such low and wide symmetrical defect distributions on Si/SiO x interfaces with ultra-thin oxide layers have up to now only been achieved by much more complex processes like by exposure to thermalized atomic oxygen under UHV conditions [27] or at interfaces of thicker (~ 10 nm) thermal oxides [28]. In order to investigate the passivation stability of the RTO SiO x -nanolayer, the SPV measurement was repeated after 4 weeks of storage under ambient conditions.…”

Section: The Interface State Distribution D It (E)mentioning

confidence: 99%

High quality tunneling oxides for passivated contacts and heterojunctions for high efficiency silicon solar cells

Gad

Vossing

Balamou

et al. 2015

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)

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We analyze the chemical passivation quality of silicon oxide-nanolayers on crystalline silicon wafers prepared by different oxidation methods with surface photo voltage and quasisteady-state photo conductance measurements. It is shown that for wet chemical oxidation and plasma oxidation, adequate passivation of the interface defects is achieved by subsequent anneal in forming gas environment. Furthermore, we present a simple oxidation method by means of rapid thermal oxidation, which requires no complex surface pre-treatment or surface preconditioning after cleaning. By rapid thermal oxidation (RTO) in a gaseous mixture of argon and oxygen and subsequent anneal in forming gas, a reproducible preparation method of high-quality ultra-thin oxide-nanolayers with a nearly intrinsic energetic distribution of interface states and a defect density of states of only 1 x 10 12 cm -2 eV -1 at the minimum of the distribution is demonstrated.

show abstract

Electronic interface properties of silicon substrates after ozone based wet-chemical oxidation studied by SPV measurements

Cited by 20 publications

References 25 publications

Double-Sided Passivated Contacts for Solar Cell Applications: An Industrially Viable Approach Toward 24% Efficient Large Area Silicon Solar Cells

Double-Sided Passivated Contacts for Solar Cell Applications: An Industrially Viable Approach Toward 24% Efficient Large Area Silicon Solar Cells

Improved Si/SiOx interface passivation by ultra-thin tunneling oxide layers prepared by rapid thermal oxidation

High quality tunneling oxides for passivated contacts and heterojunctions for high efficiency silicon solar cells

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