Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

Yang, Guangtao; Ingenito, Andrea; Hameren, Nienke van; Isabella, Olindo; Zeman, Miro

doi:10.1063/1.4940364

Cited by 52 publications

(39 citation statements)

References 8 publications

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“…Some wafers are chemically textured on both sides in an alkaline solution containing H 2 O, TMAH, and Alkatex to obtain random pyramids. Before processing, we remove the native oxide via a short HF dip, and afterwards, we wet‐chemically oxidize the c‐Si surfaces using a nitric acid solution to grow an approximately 1.5‐nm‐thick SiO 2 buffer layer as described in Yang et al The samples are then coated with intrinsic amorphous silicon layer deposited by a Tempress LPCVD reactor at a temperature of 580°C, pressure of 150 mTorr, and SiH 4 flow of 45 sccm. The deposition time is adapted to obtain layers with thickness of 250, 75, 35, and 20 nm.…”

Section: Methodsmentioning

confidence: 99%

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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In this work, we develop SiOx/poly‐Si carrier‐selective contacts grown by low‐pressure chemical vapor deposition and boron or phosphorus doped by ion implantation. We investigate their passivation properties on symmetric structures while varying the thickness of poly‐Si in a wide range (20‐250 nm). Dose and energy of implantation as well as temperature and time of annealing were optimized, achieving implied open‐circuit voltage well above 700 mV for electron‐selective contacts regardless the poly‐Si layer thickness. In case of hole‐selective contacts, the passivation quality decreases by thinning the poly‐Si layer. For both poly‐Si doping types, forming gas annealing helps to augment the passivation quality. The optimized doped poly‐Si layers are then implemented in c‐Si solar cells featuring SiO2/poly‐Si contacts with different polarities on both front and rear sides in a lean manufacturing process free from transparent conductive oxide (TCO). At cell level, open‐circuit voltage degrades when thinner p‐type poly‐Si layer is employed, while a consistent gain in short circuit current is measured when front poly‐Si thickness is thinned down from 250 to 35 nm (up to +4 mA/cm2). We circumvent this limitation by decoupling front and rear layer thickness obtaining, on one hand, reasonably high current (JSC‐EQE = 38.2 mA/cm2) and, on the other hand, relatively high VOC of approximately 690 mV. The best TCO‐free device using Ti‐seeded Cu‐plated front contact exhibits a fill factor of 75.2% and conversion efficiency of 19.6%.

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Section: Methodsmentioning

confidence: 99%

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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“…Interdigitated back contact (IBC) crystalline silicon solar cells are attracting much attention in the solar cells research society due to their potential to achieve a high power conversion efficiency by eliminating the shading losses altogether through putting both contacts on the rear of the cells [1,2]. Many institutes such as Fraunhofer ISE, ECN, and ISC-Konstanz are now working on IBC solar cells and their commercialization [3,4].…”

Section: Introductionmentioning

confidence: 99%

Efficient Low-Cost IBC Solar Cells with a Front Floating Emitter: Structure Optimization and Passivation Layer Study

et al. 2018

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Abstract:In this paper, we investigate interdigitated back contact solar cells with the front floating emitter structure systematically by using simulated and experimental methods. By comparing the front floating emitter structure with the front surface field structure, it is found that the efficiency of solar cells with the front surface field structure quickly reduces with the increasing of back surface field width; while solar cells with the front floating emitter structure can have a wider front surface field width range with minimum impact on the cell efficiency. More importantly, solar cells with the front floating emitter structure have a larger fabrication process tolerance, especially for the back surface field width, emitter width, and the bulk resistivity, which means that the fabrication process flow can be simplified and the production cost can be reduced. Based on the above results, large area (156.75 mm × 156.75 mm) interdigitated back contact solar cells with the front floating emitter structure are fabricated by using the simplified process with only one masking step. SiO x :B is used as the passivation layer, which can lead to a higher open circuit voltage and lower surface saturation current density. Finally, an efficiency of 20.39% is achieved for the large area solar cells.

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“…The rear hole-and electron-selective contact interfaces are planar and disconnected by a 1-μm-large curved gap that results from the self-aligned process [22]. To passivate the rear side of c-Si absorber bulk, a 1.5-nm-thick tunneling SiO 2 layer is formed by means of nitric acid oxidation of silicon [54]. The front surface field (FSF) is formed by phosphorus implantation.…”

Section: Simulation Methodologymentioning

confidence: 99%

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

Procel

Yang

Isabella

et al. 2019

IEEE J. Photovoltaics

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This paper presents an analysis of physical mechanisms related to operation and optimization of interdigitated back contact (IBC) poly-silicon-based devices. Concepts of carrier selectivity and tunneling are used to identify the parameters that impact on the fill factor. Then, based on technology computer-aided design (TCAD) numerical simulations, we describe the device performance in terms of transport and passivation. A validation of the model is performed by matching measured and simulated R, T, and external quantum efficiency spectra and electrical parameters. As result of such process, the opto-electrical losses of the reference device are identified. Then, we execute a study of the impact of process parameters on the performance of the IBC device under analysis. Assuming a uniform SiO 2 layer, simulation results reveal that both n-type and p-type poly-Si contacts can be theoretically perfect (i.e., approx. lossless), if assuming no interface recombination but considering tunneling of both carrier types. In other words, there exists an optimum oxide thickness (1 nm) for which majority carriers tunneling works already very well, and minority tunneling is still low enough to not result in significant recombination. Moreover, SiO 2 thickness up to maximum 1.6 nm is crucial to achieve high efficiency. Regarding rear geometry analysis, the efficiency curve as a function of emitter width peaks at 70% of pitch coverage. Further, it is shown that diffused dopants inside crystalline silicon make the device resilient to passivation quality. Finally, the calibrated model is used to perform an optimization study aiming at calculating the performance limit. The estimated performance limit is 27.3% for a 100-μm-thick bulk, 20-nm-thick poly-silicon layers, silver as rear contact, and double ARC. where he worked on advanced opto-electrical simulations of interdigitated back contacted solar cells. Since 2017, he has been with the Delft University of Technology as a Postdoctoral Researcher focusing on design and development of silicon heterojunction solar cells. His research interests include opto-electrical simulations and design of solar cells and semiconductor devices.Guangtao Yang received the Ph.D. degree from the Delft University of Technology, Delft, The Netherlands, in 2015, for his research on high-efficiency n-i-p thin-film silicon solar cells.Between 2015 and 2017, he was a Postdoctoral Researcher with the Delft University of Technology, focusing on poly-Si carrier-selective passivating contacts and their application in high-efficiency interdigital back-contacted c-Si solar cells. From January 2018 to June 2018, he was a Postdoctoral Researcher with the Eindhoven University of Technology. Since July 2018, he has been with the Delft University of Technology, working on carrier-selective passivating contacts based on poly-Si and its alloys, and transition metal-oxides.Olindo Isabella received the Ph.D. degree (cum laude) from the

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Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

Cited by 52 publications

References 8 publications

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Efficient Low-Cost IBC Solar Cells with a Front Floating Emitter: Structure Optimization and Passivation Layer Study

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

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