Etch-back of p+ Structures for Selective Boron Emitters in n-type c-Si Solar Cells

Schiele, Yvonne; Joos, Sebastian; Hahn, Giso; Terheiden, Barbara

doi:10.1016/j.egypro.2014.08.086

Cited by 17 publications

(6 citation statements)

References 10 publications

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“…In this regard, optimization of diffusion technology to form good-quality p-n junctions is the basis for realizing the high-efficiency potential of n-types and must be emphasized in the future. This is because the formation of p + diffused layers using BBr 3 is expected to maintain about 85% of the market share until 2029, as there is no viable alternative available [3, [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

et al. 2020

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In this paper, the relationship between coordination complexes and electrical properties according to the bonding structure of boron and silicon was analyzed to optimize the p–n junction quality for high-efficiency n-type crystalline solar cells. The p+ emitter layer was formed using boron tribromide (BBr3). The etch-back process was carried out with HF-HNO3-CH3COOH solution to vary the sheet resistance (Rsheet). The correlation between boron–silicon bonding in coordination complexes and electrical properties according to the Rsheet was analyzed. Changes in the boron coordination complex and boron–oxygen (B–O) bonding in the p+ diffused layer were measured through X-ray photoelectron spectroscopy (XPS). The correlation between electrical properties, such as minority carrier lifetime (τeff), implied open-circuit voltage (iVoc) and saturation current density (J0), according to the change in element bonding, was analyzed. For the interstitial defect, the boron ratio was over 1.8 and the iVoc exceeded 660 mV. Additional gains of 670 and 680 mV were obtained for the passivation layer AlOx/SiNx stack and SiO2/SiNx stack, respectively. The blue response of the optimized p+ was analyzed through spectral response measurements. The optimized solar cell parameters were incorporated into the TCAD tool, and the loss analysis was studied by varying the key parameters to improve the conversion efficiency over 23%.

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Section: Introductionmentioning

confidence: 99%

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

et al. 2020

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“…Because BBr 3 diffusion always results in a nonuniform sheet resistance. 24,25) The nonuniform boron sheet resistance was also reported for the spin-on boron diffusion method, 26) and in both cases, the variation in the sheet resistance causes a variation in the lifetime. Figure 3 shows the saturation current density J 0e mapping of the p + np + symmetrical wafer that was measured in this study.…”

Section: Resultsmentioning

confidence: 83%

Internal quantum efficiency mapping analysis for a >20%-efficiency n-type bifacial solar cell with front-side emitter formed by BBr₃ thermal diffusion

Simayi¹,

Mochizuki²,

Kida³

et al. 2017

Jpn. J. Appl. Phys.

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This paper presents a large-area (239-cm2) high-efficiency n-type bifacial solar cell that is processed using tube-furnace thermal diffusion employing liquid sources BBr3 for the front-side boron emitter and POCl3 for the rear-side phosphorus back surface field (BSF). The SiNx/Al2O3 stack was applied to the front-side boron emitter as a passivation layer. Both the front and rear-side electrodes are obtained using screen-printed contacts with H-patterns. The resulting highest-efficiency solar cell has front- and rear-side efficiencies of 20.3 and 18.7%, respectively, while the corresponding bifaciality is up to 92%. Finally, the passivation quality of the SiNx/Al2O3 stack on the front-side boron emitter and rear-side phosphorus BSF is investigated and visualized by measuring the internal quantum efficiency mapping of the bifacial solar cell.

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“…Depth d, maximum near-surface doping concentration N max , as well as the resulting doping profile could have an impact on shunting behavior. As higher R Pvalues for selectively doped, and thus deeper boron-doped emitters have been reported by Schiele et al [10], further investigations need to be performed to investigate whether or not the emitter depth is the only significant parameter.…”

Section: Resultsmentioning

confidence: 93%

Reverse Bias Behavior of Diffused and Screen-Printed n-Type Cz-Si Solar Cells

Lohmüller

Fertig

Werner

et al. 2014

IEEE J. Photovoltaics

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In this study, we investigate current flow in reverse bias mode and its impact on conversion efficiency for large-area n-type Cz-Si H-pattern and n-type Cz-Si metal wrap through (MWT) solar cells. Shunting is studied as a function of the boron emitter doping profile, and by comparing MWT cells with two different phosphorus-doped back surface field (BSF) structures. Less shunting is observed for cells with deeper boron-doped emitters (depth d ≈ 700 nm) compared to cells with shallower emitters (d ≈ 500 nm). Cells with deeper doping profile have initial shunt resistances of R P > 30 kΩcm² (without prior reverse load), while cells with shallower emitters exhibit initial values of R P ≈ 9 kΩcm², irrespective of the cell type. Furthermore, cells with deeper boron doping profiles show significantly lower current flows under reverse bias. We observe a halving of the R Pvalues after reverse biasing the H-pattern and the MWT cells with structured BSF where, on the other hand, the conversion efficiencies are hardly affected. MWT cells featuring a BSF below the external p-type contacts show a drop in conversion efficiency of 0.3% abs . This is due to degradation of the electrical insulation between via paste and BSF after reverse bias stress.

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Etch-back of p+ Structures for Selective Boron Emitters in n-type c-Si Solar Cells

Cited by 17 publications

References 10 publications

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

Internal quantum efficiency mapping analysis for a >20%-efficiency n-type bifacial solar cell with front-side emitter formed by BBr₃ thermal diffusion

Reverse Bias Behavior of Diffused and Screen-Printed n-Type Cz-Si Solar Cells

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Etch-back of p+ Structures for Selective Boron Emitters in n-type c-Si Solar Cells

Cited by 17 publications

References 10 publications

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

Correlation between Boron–Silicon Bonding Coordination, Oxygen Complexes and Electrical Properties for n-Type c-Si Solar Cell Applications

Internal quantum efficiency mapping analysis for a >20%-efficiency n-type bifacial solar cell with front-side emitter formed by BBr3 thermal diffusion

Reverse Bias Behavior of Diffused and Screen-Printed n-Type Cz-Si Solar Cells

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Internal quantum efficiency mapping analysis for a >20%-efficiency n-type bifacial solar cell with front-side emitter formed by BBr₃ thermal diffusion