Al-alloyed local contacts for industrial PERC cells by local printing

Chen, Yifeng; Altermatt, Pietro P.; Dong, Jianwen; Shu, Zhang; Liu, Jiajing; Chen, Daming; Deng, Weiwei; Jiang, Yi; Liu, Binhui; Xiao, Wenming; Zhu, Huijun; Chen, Hui; Jiao, Haijun; Pan, Xiujuan; Zhong, Ming; Wang, Dianlei; Sheng, Jian; Ying-Bin, Zhang; Shen, Hui; Zhu, Feng; Verlinden, Pierre J.

doi:10.1109/pvsc.2014.6925645

Cited by 9 publications

(6 citation statements)

References 7 publications

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“…In a first attempt the best fit is obtained considering a homogeneous surface recombination velocity of S void = 2 × 10 4 cm s −1 . This value is in good agreement with SENTAURUS numerical simulations by Chen et al . The results of the LBIC measurements and the corresponding simulation are shown in Fig.…”

Section: Resultssupporting

confidence: 90%

“…Up to now, only few numerical simulations concerning passivation of local contacts have been carried out. These simulations demonstrate that a sufficiently thick local BSF layer is needed to achieve low values for SRV . This requirement is fulfilled in the case of filled contacts where in general a BSF layer with a thickness of several micrometres exists.…”

Section: Introductionmentioning

confidence: 74%

“…The application of scanning electron microscopy (SEM) has been a common method to categorize contacts and voids in particular . However, SEM imaging requires a high effort for sample preparation and the obtained cross‐sectional views give only little information concerning the spatial distribution of voids within a large area PERC solar cell.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of local Al‐contacts by light beam induced current measurements and their verification by 2D simulation using flexPDE

Horbelt

Micard

Keller

et al. 2016

Physica Status Solidi (a)

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In recent years the relevance of passivated emitter and rear contact solar cells for industrial application increased due to significantly higher cell efficiencies compared to full area back surface field solar cells. However, the formation of local Al contacts is particularly sensitive to the manufacturing process parameters. Under non-optimized conditions, the eutectic in local Al contacts is missing and so-called voids are formed. So far, their impact onto the electrical parameters of the solar cells is not fully understood, mainly because of their difficult spatially resolved detection. Within this work the application of scanning acoustic microscopy circumvents this difficulty and allows a classification of local contacts in terms of "voids" or "filled contacts" on large cell area. The passivation quality of the BSF in the local contacts is investigated in detail through the local internal quantum efficiency (IQE) measured by light beam induced current (LBIC). It is found that there is a large spreading for the IQE values, attributed to a variation in BSF layer thickness. In addition, LBIC measurements of voids are fitted by 2D simulations, according to a detailed modelling of the surface recombination velocities (SRV) in local contacts. The final model is based on a nonuniform SRV in the void's vicinity, attributed to laser damage close to the interface. It is demonstrated that the electrical parameters of the solar cell are affected by voids only when their surface is not sufficiently passivated by a local BSF.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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Characterization of local Al‐contacts by light beam induced current measurements and their verification by 2D simulation using flexPDE

Horbelt

Micard

Keller

et al. 2016

Physica Status Solidi (a)

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“…SEMDCI has now been used widely to characterize industrial Si wafers with p‐type (boron) diffused emitters [ 18–22 ] and aluminum localized back surface contacts (LBSF). [ 23–33 ] However, reports of SEMDCI imaging of phosphorus emitters are less common, including homogeneous diffused emitters, [ 34–36 ] and localized selective emitters. [ 20,37 ] A more recent PV application of SEMDCI imaging has been characterizing nanotextured BSi.…”

Section: Introductionmentioning

confidence: 99%

“…SEMDCI has now been used widely to characterize industrial Si wafers with p-type (boron) diffused emitters [18][19][20][21][22] and aluminum localized back surface contacts (LBSF). [23][24][25][26][27][28][29][30][31][32][33] However, reports of SEMDCI Phosphorous dopant diffusion profiles feature in many silicon semiconductor devices, including the vast majority of silicon solar cells. Accurate spatially resolved dopant profiling is crucial for understanding the performance of these diffused regions, however, it is very challenging to obtain such profiles in non-planar samples.…”

mentioning

confidence: 99%

Scanning Electron Microscopy Dopant Contrast Imaging of Phosphorus‐Diffused Silicon

Zhang

Scardera

Wang

et al. 2022

Adv Materials Technologies

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Phosphorous dopant diffusion profiles feature in many silicon semiconductor devices, including the vast majority of silicon solar cells. Accurate spatially resolved dopant profiling is crucial for understanding the performance of these diffused regions, however, it is very challenging to obtain such profiles in non‐planar samples. Scanning electron microscopy for dopant contrast imaging (SEMDCI), where the secondary electron (SE) image contrast is used to determine the dopant level of a semiconductor sample, is an ideal candidate for Si dopant profiling, especially for silicon samples with surface nanotexturing or black silicon (BSi) technology. However, in previous SEMDCI studies, the dopant concentration of heavily doped n‐type layers in silicon samples have shown a poor correlation with the SE signal contrast. In this work, 1) good contrast for n‐type diffused silicon without contrast‐enhancing techniques; 2) a new contrast definition to account for imaging non‐uniformities; 3) clear correlations between SE contrast and sample work function for phosphorus‐diffused planar silicon specimens across a wide range of emitter profiles; 4) implementation of an empirical baseline correction to normalize scanning electron microscopy image condition variations, are presented. This SEMDCI method is subsequently used for the first time to obtain 2D electron concentration maps for both planar and BSi samples.

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Improved Localized Laser Doping of Boron‐Doped Si Paste for High‐Efficiency Solar Cells

Qian,

Shen,

Qian

et al. 2023

Energy Tech

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Laser doping (LD) of born‐doped Si paste (Si paste) is a potential boron‐doping approach for advanced solar cells. It is aimed to develop a top‐hat LD instead of a Gaussian LD and a rear‐side polishing process to fabricate P++ local contacts for improved passivated emitter and rear contact (i‐PERC) cells. With the help of vision alignment, LD is conducted on a dashed line pattern of printed Si paste, which decreases the consumption of paste. The variations of boron content in Si paste and the laser pulse energy density can help customize the doping profile. The predicted result of the boron LD profile is a peak dopant density of 2 × 1019 atoms cm−3 and a dopant depth of over 4.0 μm. When higher firing temperature, it can obtain thicker localized back surface field of over 7 μm, since the gradient of the residual Si concentration at the Al/Si interface can suppress the formation of voids. The overall increment in fill factor, short‐circuit current, and open‐circuit voltage enhances the average efficiency by 0.11% for i‐PERC cells and 0.09% for i‐bifacial PERC cells, respectively, due to the improved local contacts.

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Al-alloyed local contacts for industrial PERC cells by local printing

Cited by 9 publications

References 7 publications

Characterization of local Al‐contacts by light beam induced current measurements and their verification by 2D simulation using flexPDE

Characterization of local Al‐contacts by light beam induced current measurements and their verification by 2D simulation using flexPDE

Scanning Electron Microscopy Dopant Contrast Imaging of Phosphorus‐Diffused Silicon

Improved Localized Laser Doping of Boron‐Doped Si Paste for High‐Efficiency Solar Cells

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