Microscale Spatially Resolved Characterization of Highly Doped Regions in Laser-Fired Contacts for High-Efficiency Crystalline Si Solar Cells

Roigé, Anna; Alvarez, José; Kleider, Jean‐Paul; Martı́n, I.; Alcubilla, R.; Vega, Lourdes F.

doi:10.1109/jphotov.2015.2392945

Cited by 15 publications

(15 citation statements)

References 19 publications

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“…The red shift at the central part of the laser spot, which increases for a LPRs performed at 2 W (gray spectrum with crossed points), is representative of a stressed Si structure [22], and can be induced by the laser processing. These conclusions are in agreement with an exhaustive micro-Raman spectroscopy analysis of LPRs presented elsewhere [9]. In particular, such study reveals that c-Si structure only suffers structural changes inside the laser-processed spot, but not at the surrounding regions.…”

Section: B Laser-induced Impact On the C-si Wafersupporting

confidence: 92%

“…This fact has been demonstrated by the detection of dislocations [7] and certain levels of mechanical stress [8], [9] in the regions processed by laser. In addition to these micro-structural studies, other analysis such as the study of the composition [10], the estimation of the doping level [8], [9], and the study of the electronic properties [11], [12] of LPRs have been also carried out in the last years. Most of these investigations are exclusively focused on the study of the features and properties of the locally molten material volume, however, no detailed analyses at the surrounding area of LPRs have been performed up to now.…”

Section: Introductionmentioning

confidence: 92%

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Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Roigé

Ossó

Martı́n

et al. 2016

IEEE J. Photovoltaics

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Laser firing processes have emerged as a technologically feasible approach to fabricate local point contacts or local doped regions in advanced high-efficiency crystalline-Si (c-Si) solar cells. In this work we analyze the local impact induced by the laser pulse on the passivation layers, which are commonly present in advanced c-Si solar cell architectures to reduce surface recombination. We use micro-photoluminescence (PL) measurements with a spatial resolution of 7 µm to evaluate the passivation performance at the surroundings of laser processed regions (LPRs). In particular, we have studied LPRs performed on SiCx/Al2O3-and Al2O3-passivated c-Si wafers by an IR (1064 nm) laser. Micro-PL results show that passivation quality of c-Si surface is affected up to about 100 µm away from the LPR border, and that the extension of this damaged zone is correlated to the laser power and to the presence of capping layers. In the final part of the work, the observed decrease in passivation quality is included into an improved 3D simulation model that gives accurate information about the recombination velocities associated to the studied LPRs.

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Section: B Laser-induced Impact On the C-si Wafersupporting

confidence: 92%

Section: Introductionmentioning

confidence: 92%

Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Roigé

Ossó

Martı́n

et al. 2016

IEEE J. Photovoltaics

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“…The proposed method for R base determination is particularly well suitable for rear contact techniques where the real electrical contact size is not accurately known, as in laser fired contacts. In fact, recently a micro-scale study of the doping density distribution along the laser processed spots has been reported with evidences of low doped regions in the spot perimeter [33]. All this information is very important for an accurate development of these devices, in particular for the optimum pitch determination, and illustrates the usefulness of the method proposed in this work.…”

Section: Results On Experimental Samplesmentioning

confidence: 60%

Experimental determination of base resistance contribution for point-like contacted c-Si solar cells using impedance spectroscopy analysis

Orpella

Martı́n

López-González

et al. 2015

Solar Energy Materials and Solar Cells

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Abstract:One of the most common strategies in high-efficiency crystalline silicon (c-Si) solar cells for the rear surface is the combination of a dielectric passivation with a point-like contact to the base. In such devices, the trade-off between surface passivation and ohmic losses determines the optimum distance between contacts or pitch. Given a certain pitch, the series resistance related to majority carrier flow through the base and the rear point-like contact (R base ) is commonly calculated a-priori and not crosschecked in finished devices, since typical techniques to measure series resistance lead to an unique value that includes all ohmic losses. In this work, we present a novel method to measure R base using impedance spectroscopy (IS) analysis. The IS data at high frequencies allow to determine R base due to the presence of the capacitor formed by the metal/dielectric/semiconductor structure that covers most of the rear surface. The method is validated by device simulations where the dependence of R base on carrier injection, base resistivity and pitch are reproduced. Finally, R base is measured on finished devices. As a result, a more accurate value of the contacted area is deduced which is a valuable information for further device optimization.

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“…Despite the fact that this methodology can be applied to room-temperature measurements, it is more precise for cryogenic temperature studies where the contribution of phonon energies to indirect radiative transitions is much lower and then the resulting narrower PL lines can be more precisely fitted. As presented elsewhere, 12 we propose an alternative and simple PL method for studying variations in doping densities at room temperature. Figure 4 shows the normalized PL spectra recorded at room temperature from calibrated p-type c-Si wafers with different doping densities, i.e., 7 Â 10 17 , 5 Â 10 18 , 4 Â 10 19 , and 1 Â 10 20 cm À3 .…”

Section: B Doping Density Quantification Via Micro-pl Spectroscopymentioning

confidence: 99%

“…8 Confocal micro-PL spectroscopy has become during the last few years an important experimental tool for developing novel and comprehensive studies of advanced solar cell concepts 9 with micron resolution. In particular, micro-PL measurements have been extensively used to perform highresolution spatially resolved studies of different properties and material features, including the analysis of microstructural defects, 10 the estimation of doping densities, 11,12 and the detection of precipitates and impurities. 13 In confocal micro-PL measurements, a laser light is focused onto the surface of the sample to be studied by microscope objectives, and the backscattered PL signal is collected via a confocal aperture.…”

Section: Introductionmentioning

confidence: 99%

Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon

Roigé

Alvarez

Jaffré

et al. 2017

Journal of Applied Physics

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Confocal micro-photoluminescence (PL) spectroscopy has become a powerful characterization technique for studying novel photovoltaic (PV) materials and structures at the micrometer level. In this work, we present a comprehensive study about the effects and implications of photon reabsorption phenomena on confocal micro-PL measurements in crystalline silicon (c-Si), the workhorse material of the PV industry. First, supported by theoretical calculations, we show that the level of reabsorption is intrinsically linked to the selected experimental parameters, i.e., focusing lens, pinhole aperture, and excitation wavelength, as they define the spatial extension of the confocal detection volume, and therefore, the effective photon traveling distance before collection. Second, we also show that certain sample properties such as the reflectance and/or the surface recombination velocity can also have a relevant impact on reabsorption. Due to the direct relationship between the reabsorption level and the spectral line shape of the resulting PL emission signal, reabsorption phenomena play a paramount role in certain types of micro-PL measurements. This is demonstrated by means of two practical and current examples studied using confocal PL, namely, the estimation of doping densities in c-Si and the study of back-surface and/or back-contacted Si devices such as interdigitated back contact solar cells, where reabsorption processes should be taken into account for the proper interpretation and quantification of the obtained PL data. Published by AIP Publishing.

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Microscale Spatially Resolved Characterization of Highly Doped Regions in Laser-Fired Contacts for High-Efficiency Crystalline Si Solar Cells

Abstract: Abstract-Laser-fired contact (LFC) processes have emerged as

Cited by 15 publications

References 19 publications

Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Experimental determination of base resistance contribution for point-like contacted c-Si solar cells using impedance spectroscopy analysis

Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon

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