Resistivity profiles in multicrystalline silicon ingots featuring gallium co-doping

Søndenå, Rune; Haug, Halvard; Song, Adolphus; Hsueh, Chen-Chih; Odden, Jan Ove

doi:10.1063/1.5049335

Cited by 9 publications

(6 citation statements)

References 20 publications

(8 reference statements)

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“…This gives rather symmetrical resistivity profiles along 1.3 Ω cm for Ref 1.3 and Comp 1.3 with a crossing resistivity near 60 % of the relative height. Gallium starts being the dominant dopant in the very top part of the ingot which decreases dramatically the resistivity [9]. This is not shown in Fig.…”

Section: A Resistivity Profilesmentioning

confidence: 85%

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Experimental Investigation of the Optimal Ingot Resistivity for both the Cell Performances and the Temperature Coefficients for Different Cell Architectures

Berthod

Sondergaard

Odden

2018

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC &Amp

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Compensation engineering enables the achievement of lower ingot resistivities with relatively constant performances along the ingot height. In this paper the impact of the bulk resistivity on the cell performances and the temperature coefficients is investigated for compensated and non-compensated multicrystalline silicon. Based on experimental data we show that reducing the bulk resistivity below a certain value improves the temperature coefficients but deteriorates the cell performances for two distinct cell architectures (Al-BSF and PERCT). Moreover this performance loss is not balanced out by the improved temperature coefficient for operating conditions below 70 • C.

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Section: A Resistivity Profilesmentioning

confidence: 85%

“…The same amount of gallium is added in all compensated ingots and the boron concentration is varied to obtain the targeted resistivities. The description of the ingots with their initial dopant concentrations in the silicon melt (from Ref [9]) is presented in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Experimental Investigation of the Optimal Ingot Resistivity for both the Cell Performances and the Temperature Coefficients for Different Cell Architectures

Berthod

Sondergaard

Odden

2018

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC &Amp

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“…In addition, a non-compensated ingot with target resistivity of 1.3 Ωcm, made with a blend of Siemens polysilicon and fluidized bed reactor (FBR) silicon, was cast as a reference. The net doping, the resistivity profiles and the compensation levels throughout the ingot heights are shown in Figure 1 based on calculations and fitting to experimental resistivity profiles published in a previous paper [8]. Note that the three ESS ® ingots are named after their target resistivity, and that the actual resistivity is varying along the ingot height.…”

Section: Methodsmentioning

confidence: 99%

“…The typical level of phosphorus in ESS ® is 0.60 ppmw [7]. Due to the different segregation coefficients of different dopant species, a more uniform resistivity profile throughout the height of the multicrystalline ingot can be obtained by adding Ga co-doping in addition to boron (also called tri-doping), enabling a larger degree of optimization of the resistivity towards the final solar cell performance [8]- [10].…”

Section: Introductionmentioning

confidence: 99%

Simulated and measured temperature coefficients in compensated silicon wafers and solar cells

Haug

Berthod

Skomedal

et al. 2019

Solar Energy Materials and Solar Cells

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In this paper we perform a thorough investigation of the temperature coefficients of c-Si solar cells and wafers, based on both experimental data and device simulations. Groups of neighboring wafers were selected from different heights of four high performance multicrystalline silicon ingots cast using different dopants concentrations and Si feedstocks; Three different target resistivities of compensated silicon ingots based on Elkem Solar Silicon (ESS ® ), which are purified through a metallurgical route, and one non-compensated reference ingot. The wafers were processed into Al-BSF and PERCT type solar cells, as well as into lifetime samples subjected to selected solar cell processing steps before being etched down and re-passivated to assess the bulk lifetime of the final cells. Temperature-dependent photoluminescence imaging was used to study the spatial distribution of the carrier lifetime and the temperature coefficient of the lifetime. We observe a beneficial effect of higher doping levels on the temperature coefficients of the short circuit current in PERCT type cells, with the most favorable temperature coefficients are found in the ingot doped to 0.5 Ω-cm. Increasingly beneficial temperature coefficients in is also observed with increasing height in each ingot, which might be attributed to a combination of small variations in the dopant concentrations and to a clear increase in the temperature coefficient of the carrier lifetime with increasing ingot height. The latter point is also in agreement with the changes in the so-called gamma parameter of the open circuit voltage throughout the ingot. To build a more fundamental understanding of the experimental results the temperature dependence of the solar cells was simulated using PC1Dmod6.2. We find that the experimental temperature coefficients of the final cells can be reproduced in device simulations within 8 % of and 14 % for the and , respectively. The compensation level itself is of minor importance for the cell performance. Instead, the simulations indicate that the observed behavior in the temperature coefficients of the solar cells is mostly explained by differences in the net doping and carrier lifetime of the wafers.

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“…Traces of Ga may arise from the use of a small fraction of compensated silicon in the feedstock. 53 The vibrational lines of these defects were not detected in measurements at RT, most likely due to their low concentrations. Furthermore, the H-B and H-Ga vibrational lines are extremely weak in both the initial and the regenerated states of the nonhydrogenated reference wafers.…”

Section: Journal Of Applied Physicsmentioning

confidence: 98%

Hydrogen-related defects measured by infrared spectroscopy in multicrystalline silicon wafers throughout an illuminated annealing process

Weiser

Monakhov

Haug

et al. 2020

Journal of Applied Physics

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Hydrogen (H) is thought to be strongly involved in the light and elevated temperature-induced degradation observed predominantly in p-type silicon wafers, but the nature of the defect or defects involved in this process is currently unknown. We have used infrared (IR) spectroscopy to detect the vibrational signatures due to the H-B, H-Ga, and H 2 *(C) defects in thin, hydrogenated, p-type multicrystalline silicon wafers after increasing the optical path length by preparation and polishing the edges of a stack of wafers. The concentrations of the H-B and H-Ga acceptor complexes are reduced to 80% of their starting values after low intensity (5 mW/cm 2) illumination at room temperature for 96 h. Subsequent high intensity illumination (70 mW/cm 2) at 150°C for 7-8 h further decreases the concentrations of these defects; to ∼40% (H-B) and ∼50% (H-Ga) of their starting values. Our results show that, with careful sample preparation, IR spectroscopy can be used in conjunction with other techniques, e.g., quasisteady-state photoconductance, to investigate the involvement of different H-related point defects on degradation in solar-grade silicon wafers.

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Resistivity profiles in multicrystalline silicon ingots featuring gallium co-doping

Cited by 9 publications

References 20 publications

Experimental Investigation of the Optimal Ingot Resistivity for both the Cell Performances and the Temperature Coefficients for Different Cell Architectures

Experimental Investigation of the Optimal Ingot Resistivity for both the Cell Performances and the Temperature Coefficients for Different Cell Architectures

Simulated and measured temperature coefficients in compensated silicon wafers and solar cells

Hydrogen-related defects measured by infrared spectroscopy in multicrystalline silicon wafers throughout an illuminated annealing process

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