Analysis of hydrogenated amorphous silicon thin films and solar cells by means of Fourier Transform Photocurrent Spectroscopy

Melskens, Jimmy; Elzakker, G. van; Li, Y.; Zeman, Miro

doi:10.1016/j.tsf.2007.12.049

Cited by 33 publications

(20 citation statements)

References 14 publications

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“…It is noted that the samples do not lie on the same point of the Paschen curve as illustrated by the obvious differences in p and r d , while this is known to be a way to distinguish different types of a-Si:H and their light soaking stability [32]. However, the particular samples discussed in this work can still be compared, since the deposition conditions with the lowest and highest R values are known from previous work to yield solar cells with a significantly different light soaking stability [29,65]. The samples with R values in between 0 and 10 have been added to display possible trends with more statistical certainty.…”

Section: A Sample Definitionsmentioning

confidence: 96%

“…The VEPFIT results on as-deposited films are shown in Fig. 1 to indicate the variation in open volume deficiencies upon varying the deposition parameter R. Strikingly, increasing R leads to a decrease in S/S c-Si while it is commonly known that increasing R can yield a reduced LID [29], [60]- [63]. This implies that the extra hydrogen in the plasma when increasing R decreases the open volume that is available for the positron to reside in.…”

Section: A Detection Of Open Volume Deficiencies In As-deposited A-si:hmentioning

confidence: 98%

“…This determination is further enhanced by performing the DB-PAS measurements on the a-Si:H films on glass substrates only, since the contrast in S-W values is significantly larger between a-Si:H and glass in comparison to a-Si:H and c-Si. The H 2 -SiH 4 gas flow rate ratio, R = [H 2 ] / [SiH 4 ], was varied from R = 0 to R = 10, since it is known that the light soaking stability can be improved when increasing R [29], [60]- [63], while the responsible nanostructural reason is unclear. Note that the pressure was set at p = 0.7 mbar for the R = 0 films and p = 2 mbar for the R = 2.5-10 films, as it was not possible to ignite and sustain a stable plasma at lower pressures for the R > 0 conditions.…”

Section: A Sample Definitionsmentioning

confidence: 99%

See 2 more Smart Citations

Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon During Annealing

Melskens

Eijt

Schouten

et al. 2017

IEEE J. Photovoltaics

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Section: A Sample Definitionsmentioning

confidence: 96%

Section: A Detection Of Open Volume Deficiencies In As-deposited A-si:hmentioning

confidence: 98%

Section: A Sample Definitionsmentioning

confidence: 99%

See 1 more Smart Citation

Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon During Annealing

Melskens

Eijt

Schouten

et al. 2017

IEEE J. Photovoltaics

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“…A nanoscopic model for the creation of light-induced defects in the a-Si:H nanostructure is proposed. The light-induced degradation (LID) of hydrogenated amorphous silicon (a-Si:H), also known as the StaeblerWronski effect (SWE) [1,2], has been extremely thoroughly investigated in the past decades [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Although the origin of the SWE and the nature of native and metastable defects is still poorly understood, impressive progress has been made in, for instance, the development of thin-film silicon (TF Si) solar cells.…”

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confidence: 99%

Structural and electrical properties of metastable defects in hydrogenated amorphous silicon

et al. 2015

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The structural and electrical properties of metastable defects in various types of hydrogenated amorphous silicon have been studied using a powerful combination of continuous wave electron-paramagnetic resonance spectroscopy, electron spin echo (ESE) decay measurements, and Doppler broadening positron annihilation spectroscopy. The observed dependence of the paramagnetic defect density on the Doppler S parameter indicates that porous, nanosized void-rich materials exhibit higher spin densities, while dense, divacancy-dominated materials show smaller spin densities. However, after light soaking more similar spin densities are observed, indicating a long-term defect creation process in the Staebler-Wronski effect that does not depend on the a-Si:H nanostructure. From ESE decays it appears that there are fast and slowly relaxing defect types, which are linked to various defect configurations in small and large open volume deficiencies. A nanoscopic model for the creation of light-induced defects in the a-Si:H nanostructure is proposed. The light-induced degradation (LID) of hydrogenated amorphous silicon (a-Si:H), also known as the StaeblerWronski effect (SWE) [1,2], has been extremely thoroughly investigated in the past decades [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Although the origin of the SWE and the nature of native and metastable defects is still poorly understood, impressive progress has been made in, for instance, the development of thin-film silicon (TF Si) solar cells. Record initial and stable conversion efficiencies of 16.3%[22] and 13.4%-13.6% [23,24], respectively, have been reported for small area (∼1 cm 2 ) solar cells, all in triple-junction configuration. However, the amorphous junction produces most of the power in such solar cells, which means that fundamentally understanding the SWE is still important when aiming to increase the conversion efficiency of TF Si solar cells. Successfully applied LID-reduction methods include hydrogen (H 2 ) dilution of the silane gas (SiH 4 ) used during the plasma-enhanced chemical vapor deposition (PECVD) [25,26] and the use of a triode PECVD reactor [27,28]. However, the film growth follows such a complex interplay of deposition, etching, and hydrogen (H) effusion that the precise role of H in the a-Si:H nanostructure and the SWE remains obscured, although various growth models have been proposed [29].

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“…Therefore, the light-induced (meta-stable) changes in the atomic structure of the silicon matrix, such as related to the Staebler-Wronski effect [3][4][5][6][7], need to be prevented or strongly reduced. Recent studies [8,9] showed that the light-induced degradation can be suppressed by hydrogen dilution of silane during rf-PECVD growth of a-Si:H layers.…”

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confidence: 99%

Positron annihilation depth‐profiling as a promising tool for the structural analysis of light‐soaked a‐Si:H absorber layers

Eijt

Zhu

Schüt

et al. 2010

Phys. Status Solidi (c)

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Positron annihilation depth profiling is applied as a sensitive probe to investigate the defect evolution of hydrogenated amorphous silicon (a‐Si:H) absorber layers fabricated by the PE‐CVD method with typical thicknesses of 300‐500 nm. The Doppler broadening lineshape parameter S of the layers was found to depend significantly on the applied hydrogen‐to‐silane flow ratio during their deposition, related to hydrogen‐induced changes in the microstructure and local composition at the positron trapping site. Light‐soaking degradation induces a time‐dependent variation in the S parameter which seems to correlate with the evolution of defect densities extracted from FT‐Photocurrent Spectroscopy measurements. (© WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Analysis of hydrogenated amorphous silicon thin films and solar cells by means of Fourier Transform Photocurrent Spectroscopy

Cited by 33 publications

References 14 publications

Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon During Annealing

Migration of Open Volume Deficiencies in Hydrogenated Amorphous Silicon During Annealing

Structural and electrical properties of metastable defects in hydrogenated amorphous silicon

Positron annihilation depth‐profiling as a promising tool for the structural analysis of light‐soaked a‐Si:H absorber layers

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