Light-Induced Effects on the a-Si:H/c-Si Heterointerface

Vasudevan, Ravi; Poli, Isabella; Deligiannis, Dimitrios; Zeman, Miro; Smets, Arno H. M.

doi:10.1109/jphotov.2016.2633800

Cited by 6 publications

(2 citation statements)

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“…The implementation of this structure allows open‐circuit voltages ( V OC ) up to 750 mV due to an extremely low surface recombination . However, a‐Si:H is also well known to suffer from several degradation processes, for example, Staebler–Wronski (S‐W) effect, degradation under light, as well as at high temperatures, which significantly reduce its stability due to the formation of electronically active defects, most likely represented by Si dangling bonds (DBs) . The microscopic aspect of these mechanisms are still under debate but it is often linked to how hydrogen is bonded to Si in the a‐Si:H film .…”

Section: Introductionmentioning

confidence: 99%

Insights into the Degradation of Amorphous Silicon Passivation Layer for Heterojunction Solar Cells

Bernardini

Bertoni

2018

Physica Status Solidi (a)

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Heterojunction (HJ) crystalline silicon (c-Si) solar cells outstanding performance relies heavily on the excellent passivation provided by the amorphous Si (a-Si:H) layer. However, recombination at the a-Si:H/c-Si interface can vary over time and become particularly detrimental for HJ modules performance making the full understanding of the recombination mechanisms at play of paramount importance. In this work, the variation of effective lifetime for high-quality n-type FZ c-Si substrates coated with a-Si:H(i) layer after several processing steps and over a period of 28 months is tracked. The root cause for degradation is identified by experimentally evaluating the surface recombination velocity (SRV) temperature-and injection-dependence before and after degradation has occurred. By applying a model for the recombination at the a-Si:H/c-Si interface to temperature-and injection-dependent SRV data, the authors are able to assess the lifetime decay as entirely ascribed to a loss of chemical passivation. Upon re-annealing the samples, only a partial recovery of lifetime is obtained suggesting that effusion of hydrogen from the a-Si:H layer has occurred. These results indicate that the usage of a capping layer is needed whereas a thorough engineering of the a-Si:H(i) layer thickness may be necessary to avoid the loss of performance of a-Si based heterojunction structures and modules.

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Section: Introductionmentioning

confidence: 99%

Insights into the Degradation of Amorphous Silicon Passivation Layer for Heterojunction Solar Cells

Bernardini

Bertoni

2018

Physica Status Solidi (a)

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“…[18][19][20] These light-induced defects were also classified as "fast" and "slow" states of which the annealing of the "fast" states takes place right after termination of light soaking even at room temperature, [21][22][23][24][25] causing a significant room temperature recovery of the photoconductivity in films as well as in dark forward-biased current-voltage characteristics of p-i-n solar cells. 26 Additionally, it is worth noting here that very short time scale (ms-s) changes in the surface passivation quality of a-Si:H on crystalline wafers have also been reported and differently for different a-Si:H nanostructures, 27 further suggesting that there are "fast" states that should be part of a complete description of the SWE. Moreover, the conventional dual beam photoconductivity (DBP) method that was used to indirectly obtain the sub-bandgap absorption coefficient spectrum has also identified three different gap states below the Fermi level in both annealed and light-soaked states.…”

Section: Introductionmentioning

confidence: 78%

The native and metastable defects and their joint density of states in hydrogenated amorphous silicon obtained from the improved dual beam photoconductivity method

Güneş

Melskens²,

Smets

2023

Journal of Applied Physics

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In this study, undoped hydrogenated amorphous silicon (a-Si:H) thin films deposited under moderate dilution ratios of silane by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) have been investigated using steady-state photoconductivity and improved dual beam photoconductivity (DBP) methods to identify changes in multiple gap states in annealed and light-soaked states. Four different gap states were identified in annealed state named as A, B, C, and X states. The peak energy positions of these Gaussian distributions are consistent with those recently identified by Fourier transform photocurrent spectroscopy (FTPS). After in situ light soaking, their density increases with different rates as peak energy positions and half-widths remain unaffected. The electron-occupied A and B states located below the dark Fermi level and their density and ratios in the annealed and light-soaked states correlate well with those defects detected by time-domain pulsed electron paramagnetic resonance (EPR) experiments. The A, B, and X states located closer to the middle of the bandgap anneal out at room temperature in dark and define the “fast” states. However, the C states show no sign of room temperature annealing such that they must define the “slow” states in undoped a-Si:H. The results found in this study indicate that the anisotropic disordered network is a more appropriate model than previously proposed defect models based on the continuous random network to define the nanostructure of undoped a-Si:H, where multiple defects, D0 and non-D0 defects, can be identified by using the improved DBP method.

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Towards an industrial in-line solution for efficient post-treatment of silicon heterojunction solar cells

Veirman

Caron

Jeronimo

et al. 2022

Solar Energy Materials and Solar Cells

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Light-Induced Effects on the a-Si:H/c-Si Heterointerface

Abstract: Abstract-Light-induced effects on the minority carrier lifetime of silicon heterojunction structures are studied through multiple exposure photoconductance decay (MEPCD). MEPCD monitors the effect of the measurement flash from a PCD setup on a sample over thousands of measurements. Varying

Cited by 6 publications

References 30 publications

Insights into the Degradation of Amorphous Silicon Passivation Layer for Heterojunction Solar Cells

Insights into the Degradation of Amorphous Silicon Passivation Layer for Heterojunction Solar Cells

The native and metastable defects and their joint density of states in hydrogenated amorphous silicon obtained from the improved dual beam photoconductivity method

Towards an industrial in-line solution for efficient post-treatment of silicon heterojunction solar cells

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