In-situ transmission measurements as process control for thin-film silicon solar cells

Meier, Matthias; Muthmann, Stefan; Flikweert, AJ Arjan; Dingemans, G Gijs; Sanden, van de Mcm Richard; Gordijn, A.

doi:10.1016/j.solmat.2011.07.022

Cited by 10 publications

(9 citation statements)

References 14 publications

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“…Figure 2 shows an example of the transient optical transmission signal at a wavelength of 656 nm which was recorded during the deposition of μc-Si:H on an etched ZnO:Al substrate with a root mean square roughness of 110 nm. The shape of the transient transmission curve is known from our earlier studies [9,10]. We show it here again to briefly summarize the signal shape which helps to follow our further evaluation and the discussion.…”

Section: Methodsmentioning

confidence: 76%

“…The transient signal of transmission measurements, a e-mail: ma.meier@fz-juelich.de which were performed in-situ during the deposition of microcrystalline silicon, was used. In our earlier work, we have demonstrated that these transmission measurements can be used to determine the thickness and the crystallinity of the growing layers [9]. Additionally, we showed that especially by in-situ controlling the thickness of the deposited absorber layers, it was possible to fabricate tandem solar cells in which the top and bottom cell generate the identical short-circuit current density which is referred to as "current matched" [10].…”

Section: Introductionmentioning

confidence: 95%

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In-situ determination of the effective absorbance of thinμc-Si:H layers growing on rough ZnO:Al

et al. 2013

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In this study optical transmission measurements were performed in-situ during the growth of microcrystalline silicon (μc-Si:H) layers by plasma enhanced chemical vapor deposition (PECVD). The stable plasma emission was used as light source. The effective absorption coefficient of the thin μc-Si:H layers which were deposited on rough transparent conductive oxide (TCO) surfaces was calculated from the transient transmission signal. It was observed that by increasing the surface roughness of the TCO, the effective absorption coefficient increases which can be correlated to the increased light scattering effect and thus the enhanced light paths inside the silicon. A correlation between the in-situ determined effective absorbance of the μc-Si:H absorber layer and the short-circuit current density of μc-Si:H thin-film silicon solar cells was found. Hence, an attractive technique is demonstrated to study, on the one hand, the absorbance and the light trapping in thin films depending on the roughness of the substrate and, on the other hand, to estimate the short-circuit current density of thin-film solar cells in-situ, which makes the method interesting as a process control tool.

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Section: Methodsmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 95%

In-situ determination of the effective absorbance of thinμc-Si:H layers growing on rough ZnO:Al

et al. 2013

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“…In addition the Raman crystallinity of the subsurface layers (p-layer) can be increased. [46][47][48] Since the absorption coefficient of lc-Si:H depends on I RS C , 25,49 the transparency of the p-layer might be enhanced. In both cases, an increase of the charge carrier generation could cause the improved EQE for initially low SC i .…”

Section: B Effects Of Modified Raman-crystallinity During the Initiamentioning

confidence: 99%

“…21 To achieve these Raman crystallinities throughout the entire absorber layer process settings have to be adapted during the deposition of lc-Si:H. Since this requires an adequate monitoring of the Raman crystallinity, various in-situ and ex-situ measurement techniques have been applied to characterize the lc-Si:H absorber layer deposition. [8][9][10]12,13,19,[21][22][23][24][25][26][27][28] To monitor the layer growth with adequate accuracy, diagnostic methods with high depth and temporal resolution are required. For example, in-situ ellipsometry features high surface sensitivity.…”

Section: Introductionmentioning

confidence: 99%

“…8,22 However, incident angles of 70 -80 complicate the integration of the ellipsometry setup into the parallel plate reactor and data analysis becomes difficult for varying substrate morphology. 29 The plasma emission of the PECVD process is recorded with excellent temporal resolution by optical emission spectroscopy (OES), 13,25 but material properties of the growing layer are not probed. High depth resolution of the Raman crystallinity in the growth direction was achieved by KOH wet-etching or reactive ion etching.…”

Section: Introductionmentioning

confidence: 99%

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Interplay between crystallinity profiles and the performance of microcrystalline thin-film silicon solar cells studied by in-situ Raman spectroscopy

Fink

Muthmann

Mück

et al. 2015

Journal of Applied Physics

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The intrinsic microcrystalline absorber layer growth in thin-film silicon solar-cells is investigated by in-situ Raman spectroscopy during plasma enhanced chemical vapor deposition. In-situ Raman spectroscopy enables a detailed study of the correlation between the process settings, the evolution of the Raman crystallinity in growth direction, and the photovoltaic parameters η (solar cell conversion efficiency), JSC (short circuit current density), FF (fill factor), and VOC (open circuit voltage). Raman spectra were taken every 7 nm of the absorber layer growth depending on the process settings. The Raman crystallinity of growing microcrystalline silicon was determined with an absolute error of approximately ±5% for total absorber layer thicknesses >50 nm. Due to this high accuracy, inherent drifts of the Raman crystallinity profiles are resolvable for almost the entire absorber layer deposition. For constant process settings and optimized solar cell device efficiency Raman crystallinity increases during the absorber layer growth. To compensate the inhomogeneous absorber layer growth process settings were adjusted. As a result, absorber layers with a constant Raman crystallinity profile — as observed in-situ — were deposited. Solar cells with those absorber layers show a strongly enhanced conversion efficiency by ∼0.5% absolute. However, the highest FF, VOC, and JSC were detected for solar cells with different Raman crystallinity profiles. In particular, fill factors of 74.5% were observed for solar cells with decreasing Raman crystallinity during the later absorber layer growth. In contrast, intrinsic layers with favorable JSC are obtained for constant and increasing Raman crystallinity profiles. Therefore, monitoring the evolution of the Raman crystallinity in-situ provides sufficient information for an optimization of the photovoltaic parameters with surpassing depth resolution.

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In-situ Raman spectroscopy used to study and control the initial growth phase of microcrystalline absorber layers for thin-film silicon solar cells

Muthmann

Köhler

Meier

et al. 2012

Journal of Non-Crystalline Solids

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In-situ transmission measurements as process control for thin-film silicon solar cells

Cited by 10 publications

References 14 publications

In-situ determination of the effective absorbance of thinμc-Si:H layers growing on rough ZnO:Al

In-situ determination of the effective absorbance of thinμc-Si:H layers growing on rough ZnO:Al

Interplay between crystallinity profiles and the performance of microcrystalline thin-film silicon solar cells studied by in-situ Raman spectroscopy

In-situ Raman spectroscopy used to study and control the initial growth phase of microcrystalline absorber layers for thin-film silicon solar cells

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