Interaction between Metal Impurities and Small-Angle Grain Boundaries on Recombination Properties in Multicrystalline Silicon for Solar Cells

Sameshima, Takashi; Miyazaki, Naoto; Tsuchiya, Yoichi; Hashiguchi, Hiroki; Tachibana, Takeshi; Kojima, Takuto; Ohshita, Yoshio; Arafune, Koji; Ogura, Atsushi

doi:10.1143/apex.5.042301

Cited by 26 publications

(12 citation statements)

References 20 publications

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“…A notable outlier to this trend is seen in Figure 5d, where the grain boundary with greatest misorientation also had the lowest EBIC contrast after polishing. This replicates the work by Sameshima [35], who found that misorientation was not the sole indicator of recombination activity.…”

Section: Accepted Manuscriptsupporting

confidence: 90%

Identification of colloidal silica polishing induced contamination in silicon

Tweddle

Hamer

Shen

et al. 2019

Materials Characterization

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This paper presents a multiscale characterisation approach, analysing the effect of colloidal silica polishing on crystallographic defects in multicrystalline silicon. Colloidal silica polishing for as little time as 30 minutes was found to significantly increase the recombination activity of all defects, as measured by Electron Beam Induced Current Mapping. The impurities responsible for the room temperature contamination of defects due to colloidal silica polishing were Cu and Ni, as measured by Atom Probe Tomography.

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Section: Accepted Manuscriptsupporting

confidence: 90%

Identification of colloidal silica polishing induced contamination in silicon

Tweddle

Hamer

Shen

et al. 2019

Materials Characterization

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“…5 left) are assigned to low-angle GBs (misorientation angle of less than 15°) and stacking faults. It is reported that low-angle GBs are effective gettering sites for impurities due to their particular boundary dislocation structure, thus, they are strongly recombination active [24], [25]. Twin boundaries do not affect the PL signal substantially.…”

Section: Grain Boundary Characterizationmentioning

confidence: 99%

Assessment of Bulk and Interface Quality for Liquid Phase Crystallized Silicon on Glass

Trinh

Bokalič

Preissler

et al. 2019

IEEE J. Photovoltaics

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This work reports on the electrical quality of liquid phase crystallized silicon (LPC-Si) on glass for thin-film solar cell applications. Spatially resolved methods such as light beam induced current (LBIC), microwave photoconductance decay (MWPCD) mapping and electron backscatter diffraction (EBSD) were used to access the overall material quality, intra-grain quality, surface passivation and grain boundary (GB) properties. LBIC line scans across GBs were fitted with a model to characterize the recombination behavior of GBs. According to MWPCD measurement, intra-grain bulk carrier lifetimes were estimated to be larger than 4.5 µs for n-type LPC-Si with a doping concentration in the order of 10 16 cm -3 . Low-angle GBs were found to be strongly recombination active and identified as highly defect-rich regions which spatially extend over a range of 40-60 µm and show a diffusion length of 0.4 µm. Based on absorber quality characterization, the influence of intra-grain quality, heterojunction interface and GBs/dislocations on the cell performance were separately clarified based on 2D-device simulation and a diode model. High back surface recombination velocities of several 10 5 cm/s are needed to get the best match between simulated and measured open circuit voltage (Voc), indicating back surface passivation problem. The results showed that Voc losses are not only due to poor back surface passivation but also due to crystal defects such as GBs and dislocation.

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“…GB segregation would take place so as to reduce both the strain energy and the electronic GB energy (Seager, ), and effects of the segregation levels on solar cell performance have been examined for various GB structures with different tilt angles and boundary planes (Buonassisi et al ., ; Chen & Sekiguchi, ; Yu et al ., ; Sameshima et al ., ). Small‐angle tilt boundaries (SATBs), of which the tilt angle is smaller than about 10°, are composed of arrays of edge dislocations whose density is determined by the tilt angle.…”

Section: Introductionmentioning

confidence: 97%

“…In the present work, we have summarized all the APT data and constructed the comprehensive mechanism for the oxygen segregation at GBs: it is hypothesized that oxygen atoms preferentially segregate at the atomic sites under specific atomic stress so as to attain more stable bonding network by reducing the local stress. This finding would help to engineer the distribution of oxygen agglomerates at GBs in controlled fashions (Falster & Voronkov, ), as well as to control metallic contaminants by phosphorous diffusion gettering (Sameshima et al ., ; Fenning et al ., ; Seibt et al ., ) and thermal (Buonassisi et al ., ) processes, disturbed by oxygen agglomerates.…”

Section: Introductionmentioning

confidence: 98%

Nanoscopic analysis of oxygen segregation at tilt boundaries in silicon ingots using atom probe tomography combined with TEM and ab initio calculations

Ohno

Fujiwara

Kutsukake

et al. 2017

Journal of Microscopy

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We have developed an analytical method to determine the segregation levels on the same tilt boundaries (TBs) at the same nanoscopic location by a joint use of atom probe tomography and scanning transmission electron microscopy, and discussed the mechanism of oxygen segregation at TBs in silicon ingots in terms of bond distortions around the TBs. The three-dimensional distribution of oxygen atoms was determined at the typical small- and large-angle TBs by atom probe tomography with a low impurity detection limit (0.01 at.% on a TB plane) simultaneously with high spatial resolution (about 0.4 nm). The three-dimensional distribution was correlated with the atomic stress around the TBs; the stress at large-angle TBs was estimated by ab initio calculations based on atomic resolution scanning transmission electron microscopy data and that at small-angle TBs were calculated with the elastic theory based on dark-field transmission electron microscopy data. Oxygen atoms would segregate at bond-centred sites under tensile stress above about 2 GPa, so as to attain a more stable bonding network by reducing the local stress. The number of oxygen atoms segregating in a unit TB area N (in atoms nm ) was determined to be proportional to both the number of the atomic sites under tensile stress in a unit TB area n and the average concentration of oxygen atoms around the TB [O ] (in at.%) with N ∼ 50 n [O ].

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Interaction between Metal Impurities and Small-Angle Grain Boundaries on Recombination Properties in Multicrystalline Silicon for Solar Cells

Cited by 26 publications

References 20 publications

Identification of colloidal silica polishing induced contamination in silicon

Identification of colloidal silica polishing induced contamination in silicon

Assessment of Bulk and Interface Quality for Liquid Phase Crystallized Silicon on Glass

Nanoscopic analysis of oxygen segregation at tilt boundaries in silicon ingots using atom probe tomography combined with TEM and ab initio calculations

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