Quantitative evaluation of grain boundary activity in multicrystalline semiconductors by light beam induced current: An advanced model

Micard, Gabriel; Hahn, Giso; Zuschlag, Annika; Seren, Sven; Terheiden, Barbara

doi:10.1063/1.3462447

Cited by 16 publications

(20 citation statements)

References 13 publications

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“…5(c) show a consistent trend between the measured maximum PL counts after P-gettering, and distance between GBs. This appears consistent with previous modeling studies in which intragranular bulk lifetime is high and the effective lifetime is governed by point-defect recombination at or near grain boundaries [47], [48]; in such materials, the effective lifetime seldom plateaus at the true bulk lifetime, because carrier diffusion to the nearest recombination-active GB limits the effective lifetime. In contrast, when selecting grains that contain dense dislocation clusters (lower bulk lifetimes), the maximum PL counts computed is significantly depressed, as shown by the red rhomboids in Fig.…”

Section: Role Of Grain Boundaries In Differences Of Gettering Respsupporting

confidence: 78%

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

Castellanos

Ekstrøm

Autruffe

et al. 2016

IEEE J. Photovoltaics

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Abstract-In recent years, high-performance multicrystalline silicon (HPMC-Si) has emerged as an attractive alternative to traditional ingot-based multicrystalline silicon (mc-Si), with a similar cost structure but improved cell performance. Herein, we evaluate the gettering response of traditional mc-Si and HPMC-Si. Microanalytical techniques demonstrate that HPMC-Si and mc-Si share similar lifetime-limiting defect types but have different relative concentrations and distributions. HPMC-Si shows a substantial lifetime improvement after P-gettering compared with mc-Si, chiefly because of lower area fraction of dislocation-rich clusters. In both materials, the dislocation clusters and grain boundaries were associated with relatively higher interstitial iron point-defect concentrations after diffusion, which is suggestive of dissolving metal-impurity precipitates. The relatively fewer dislocation clusters in HPMC-Si are shown to exhibit similar characteristics to those found in mc-Si. Given similar governing principles, a proxy to determine relative recombination activity of dislocation clusters developed for mc-Si is successfully transferred to HPMC-Si. The lifetime in the remainder of HPMC-Si material is found to be limited by grain-boundary recombination. To reduce the recombination activity of grain boundaries in HPMC-Si, coordinated impurity control during growth, gettering, and passivation must be developed.

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Section: Role Of Grain Boundaries In Differences Of Gettering Respsupporting

confidence: 78%

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

Castellanos

Ekstrøm

Autruffe

et al. 2016

IEEE J. Photovoltaics

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“…The minority carrier distribution is obtained by solving the minority carrier diffusion equation in steady state expressed as

Δ n (r_{normalG}) - \frac{n (r_{normalG})}{L_{normaln}^{2}} = - \frac{- G (r_{normalG})}{D_{normaln}},

with Δ the Laplace operator, n the excess carrier density of the minorities, r G the generalized coordinate of the position which would be expressed by x , y , and z in 3D Cartesian coordinates . G is the generation rate distribution of charge carriers, L n the diffusion length of electrons, and D n the diffusion constant for electrons.…”

Section: Resultsmentioning

confidence: 99%

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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“…The evaluation of the exp( x 2 ) erfc( x ) like term is performed as described in the appendix of Ref. . The last term of Eq.…”

Section: Model For a Diverging Beammentioning

confidence: 99%

Injection in light beam induced current systems: An analytical model

Micard

Hahn

Terheiden

2016

Physica Status Solidi (a)

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In LBIC systems, the evaluation of the injection level is necessary when operating in low injection for defect recombination studies or in defined standard illumination conditions (one or several suns for concentrator applications) for quantum efficiency evaluation. We demonstrate in this contribution that evaluating the laser beam induced injection based on uniform illumination condition can lead to several decades of error because of the lateral carrier diffusion. Based on a parallel beam approximation, we propose here an analytical model to evaluate the maximum of injection of a laser with its parametrization valid for most LBIC system settings and material quality. State of the art high resolution LBIC (HR‐LBIC) systems have so sharply focused laser beams that the beam divergence cannot be neglected anymore in the injection calculation. Although providing a quantitative criterion to determine whether the beam divergence can be neglected, we provide a more advanced model for describing the injection of the laser that includes beam divergence.

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Quantitative evaluation of grain boundary activity in multicrystalline semiconductors by light beam induced current: An advanced model

Cited by 16 publications

References 13 publications

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

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

Injection in light beam induced current systems: An analytical model

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