A Unified Parameterization of the Formation of Boron Oxygen Defects and their Electrical Activity

Niewelt, Tim; Schön, Jonas; Broisch, Juliane; Mägdefessel, Sven; Warta, Wilhelm; Schubert, Martin C.

doi:10.1016/j.egypro.2016.07.016

Cited by 9 publications

(3 citation statements)

References 19 publications

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“…It is therefore important to compare the degraded lifetimes in indium doped silicon with boron doped equivalents. For such a comparison, we use the parameterization of degraded lifetime in boron doped silicon from Bothe et al Noting the comments of Niewelt et al, this provides a reasonable comparison to our data as it refers to the as‐delivered state, and our samples did not undergo a high temperature diffusion step which can strongly affect the effective concentration of the recombination centre which forms under LID. In Figure (b), the lifetime for all the indium doped samples is plotted in the undegraded state (“U”) after a 200°C anneal for 15 minutes, and the degraded state due to 1 Sun illumination for 1 hour (“D”).…”

Section: Results and Analysismentioning

confidence: 99%

Minority carrier lifetime in indium doped silicon for photovoltaics

Murphy

Pointon

Grant

et al. 2019

Progress in Photovoltaics

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For photovoltaics, switching the p‐type dopant in silicon wafers from boron to indium may be advantageous as boron plays an important role in the light‐induced degradation mechanism. With the continuous Czochralski crystal growth process it is now possible to produce indium doped silicon substrates with the required doping levels for solar cells. This study aims to understand factors controlling the minority carrier lifetime in such substrates with a view to enabling the quantification of the possible benefits of indium doped material. Experiments are performed using temperature‐dependent Hall effect and injection‐dependent carrier lifetime measurements. The recombination rate is found to vary linearly with the concentration of un‐ionized indium which exists in the sample at room temperature due to indium's relatively deep acceptor level at 0.15 eV from the valence band. Lifetime in indium doped silicon is also shown to degrade rapidly under illumination, but to a level substantially higher than in equivalent boron doped silicon samples. A window of opportunity exists in which the minority carrier lifetime in degraded indium doped silicon is higher than the equivalent boron doped silicon, indicating it may be suitable as the base material for front contact photovoltaic cells.

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Section: Results and Analysismentioning

confidence: 99%

Minority carrier lifetime in indium doped silicon for photovoltaics

Murphy

Pointon

Grant

et al. 2019

Progress in Photovoltaics

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“…[12][13][14][15][16] However, there is a lack of data to ascertain the validity of one model over the other and to allow for accurate modelling of the defect formation kinetics. [17][18][19][20] In this study we present new data on the effect of bias, light and temperature on the formation kinetics of the boronoxygen defect in compensated n-type silicon. 5,6) We confirm that the kinetics depend strongly on the hole concentration (minority carrier density in compensated n-type silicon).…”

Section: Introductionmentioning

confidence: 95%

Carrier induced degradation in compensated n-type silicon solar cells: Impact of light-intensity, forward bias voltage, and temperature on the reaction kinetics

Shen¹,

Sun²,

Zheng³

et al. 2017

Jpn. J. Appl. Phys.

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We analyze the formation kinetics of the boron–oxygen defect in compensated n-type upgraded metallurgical-grade (UMG) silicon solar cells. Through time-resolved open-circuit voltage measurements, we explore the influence of temperature, forward bias, and light intensity on the formation kinetics of the defect. Our results confirm that the boron–oxygen defect forms more slowly in compensated n-type silicon than in p-type silicon. We present evidence which suggests that the slower kinetics in n-type silicon may be due to a lower frequency factor for defect formation.

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“…28 This is because the injection levels at which the V OC was measured varied significantly throughout the degradation-regeneration cycle, while the recombination lifetime of the BO defects in n-Si is still injection-dependent. 29,30 Another reason is that if the carrier recombination rate at BO defects is reduced, other forms of recombination like surface recombination and Auger recombination in the heavily doped layers start to dominate the V OC to the level of the control cells. In terms of the kinetics, the regeneration was completed in approximately 30-100 s in all four UMG cells, in very similar timescales.…”

mentioning

confidence: 99%

Complete regeneration of BO-related defects in n-type upgraded metallurgical-grade Czochralski-grown silicon heterojunction solar cells

Sun

Chen

Weigand

et al. 2018

Applied Physics Letters

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Complete regeneration of boron-oxygen-related (BO) defects has been demonstrated on n-type upgraded metallurgical-grade (UMG) Czochralski-grown silicon heterojunction solar cells. Under accelerated regeneration conditions (93 suns, 220 C), V OC fully recovered in 30-100 s and remained stable during a subsequent stability test. Under milder regeneration conditions (3 suns, 180 C), the kinetics were slowed down by more than an order of magnitude, but the recovery of V OC was still complete and stable. The stabilized V OC of the UMG cells is 709 mV-722 mV, similar to the electronic-grade control cells. We conclude that a significant amount of hydrogen, sourced from the a-Si:H films and possibly the hydrogen plasma treatment, has been introduced into the bulk during the solar cell fabrication processes or the regeneration step. This results in abundant hydrogen concentrations in the bulk of the cells for the purpose of regeneration of BO defects, whether the cell was pre-fired with silicon nitride films (600 C for 5 s) or not.

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A Unified Parameterization of the Formation of Boron Oxygen Defects and their Electrical Activity

Cited by 9 publications

References 19 publications

Minority carrier lifetime in indium doped silicon for photovoltaics

Minority carrier lifetime in indium doped silicon for photovoltaics

Carrier induced degradation in compensated n-type silicon solar cells: Impact of light-intensity, forward bias voltage, and temperature on the reaction kinetics

Complete regeneration of BO-related defects in n-type upgraded metallurgical-grade Czochralski-grown silicon heterojunction solar cells

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