Quantum efficiency simulations from on-line compatible mapping of thin-film solar cells

Aryal, Puruswottam; Chen, Jie; Huang, Zhi-Quan; Dahal, Lila R.; Sestak, Michelle N.; Attygalle, Dinesh; Jacobs, R. E.; Ranjan, Vinayak; Marsillac, Sylvain; Collins, R. W.

doi:10.1109/pvsc.2011.6186402

Cited by 11 publications

(5 citation statements)

References 7 publications

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“…Further increases in reverse bias magnitude lead to no appreciable additional current collection. The cell structure in Figure , along with the component layer ε ( E ) spectra, enables simulation of the QE spectrum and integrated current density J , based on simple assumptions regarding collection from the active layers of the device . For some parameters, however, the QE measurement provides higher sensitivity than does the SE measurement, the reason being that in the QE measurement, the CdTe layer itself serves as an effective photon detector within the film stack.…”

Section: Resultsmentioning

confidence: 99%

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Koirala

Yoon

et al. 2016

Prog. Photovolt: Res. Appl.

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Polycrystalline CdS/CdTe thin-film solar cells in the superstrate configuration have been studied by spectroscopic ellipsometry (SE) using glass side illumination. In this measurement method, the first reflection from the ambient/glass interface is rejected, whereas the second reflection from the glass/film-stack interface is collected; higher order reflections are also rejected. The SE analysis incorporates parameterized dielectric functions ε for solar cell component materials obtained by in situ and variableangle SE. In the SE analysis of the complete cells, a step-wise procedure ranks the fitting parameters, including thicknesses and those defining the spectra in ε, according to their ability to reduce the root-mean-square deviation between the simulated and measured SE spectra. The best fit thicknesses from this analysis are found to be consistent with electron microscopy. Based on the SE results, the solar cell quantum efficiency (QE) can be simulated without any free parameters, and comparisons with measured QE enable optical model refinements as well as identification of optical and electronic losses. These capabilities have wide applications in photovoltaic module mapping and in-line monitoring.

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Section: Resultsmentioning

confidence: 99%

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Koirala

Yoon

et al. 2016

Prog. Photovolt: Res. Appl.

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“…The non-uniformities in the device parameters resulting from the sputter deposition process have been correlated with the device performance parameters. Furthermore, the models deduced from the RTSE studies will serve for higher accuracy on-line monitoring and more realistic quantum efficiency modeling [7].…”

Section: Discussionmentioning

confidence: 99%

Multichannel spectroscopic ellipsometry for CdTe Photovoltaics: From real-time monitoring to large-scale mapping

Koirala

Chen

Tan

et al. 2013

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC)

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Real time spectroscopy ellipsometry (RTSE) has been applied to study the evolution of thin film optical structure during sputter deposition of polycrystalline CdS/CdTe solar cell stacks on transparent conducting oxide (TCO) coated glass substrates optimized for high efficiency. RTSE provides information on (i) interface formation to the underlying high resistivity transparent (HRT) layer during initial CdS growth, (ii) bulk layer CdS growth and its surface roughness evolution, (iii) CdS/CdTe interface formation when the overlying CdTe layer is deposited on the CdS, and (iv) CdTe bulk layer growth and its roughness evolution. Structural/optical models developed in the analysis of RTSE data acquired at a single point are also applied in the analysis of ex situ mapping SE data obtained over the area of the completed solar cell stack. As a result, maps of the structural parameters can be extracted, which then can be correlated with maps of the small area device performance. When uncorrelated non-uniformities exist over the area, optimization by combinatorial methods is possible.Index Terms -CdS/CdTe, thin film solar cell, chalcogenide, spectroscopic ellipsometry.

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“…Furthermore, the multilayer stack structural parameters and associated component material dielectric functions from the database, all deduced by SE, enable simulations of the solar cell quantum efficiency. A comparison of the simulated results with the experimental quantum efficiency provides insights into the origins of recombination losses [13].…”

Section: A Overview Of Methodologymentioning

confidence: 99%

“…This equation serves as a valuable component of a database for multilayer analysis. Recently, it has been demonstrated that SE, as a single-spot measurement, can provide the thicknesses of all the component layers in the complete CIGS solar cell stack, applying just such a database obtained for these layers [13]. By performing SE in a multichannel mode with a linear array detector [14], high measurement speeds are possible that enable large-area multilayer mapping by translating the PV panel and/or the ellipsometer heads.…”

Section: Introductionmentioning

confidence: 99%

Large-area compositional mapping of Cu(In_1−xGa_x)Se₂ materials and devices with spectroscopic ellipsometry

Aryal

Attygalle

Pradhan

et al. 2012

2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2

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A spectroscopic ellipsometry (SE) capability having the potential to scan production-scale areas at high speed has been developed and successfully applied to map the alloy composition of copper-indium-gallium-diselenide (CuIn 1 −x Ga x Se 2 : CIGS) thin films. This technique not only generates a compositional map but simultaneously provides maps of the more typical SE-determined properties as well, including bulk layer and surface roughness layer thicknesses. As a result, the methodology is suitable for characterization in online production-scale applications. In order to develop the mapping capability, CIGS films having different molar Ga contents x and fixed copper stoichiometry were deposited and measured in situ by SE in order to extract the complex dielectric functions (ε = ε 1 +iε 2 ) of these films. For mathematical interpolation between the available alloy contents, the (ε 1 , ε 2 ) spectra were parameterized using an oscillator sum. Best-fitting equations were obtained that relate each oscillator parameter to the Ga content x, as determined by energy dispersive X-ray analysis. This approach reduces the number of fitting parameters for (ε 1 , ε 2 ) from several to just one: the Ga content x. Because (ε 1 , ε 2 ) is now represented by this single parameter, the chances of parameter correlations during fitting are reduced, enabling production-scale compositional mapping of chalcopyrite films by SE.Index Terms-Ellipsometry, gallium-based semiconductor materials, optical variables measurement, photovoltaic (PV) cells, semiconductor film, thickness measurement.

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Quantum efficiency simulations from on-line compatible mapping of thin-film solar cells

Cited by 11 publications

References 7 publications

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Multichannel spectroscopic ellipsometry for CdTe Photovoltaics: From real-time monitoring to large-scale mapping

Large-area compositional mapping of Cu(In_1−xGa_x)Se₂ materials and devices with spectroscopic ellipsometry

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Quantum efficiency simulations from on-line compatible mapping of thin-film solar cells

Cited by 11 publications

References 7 publications

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Through-the-glass spectroscopic ellipsometry for analysis of CdTe thin-film solar cells in the superstrate configuration

Multichannel spectroscopic ellipsometry for CdTe Photovoltaics: From real-time monitoring to large-scale mapping

Large-area compositional mapping of Cu(In1−xGax)Se2 materials and devices with spectroscopic ellipsometry

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Large-area compositional mapping of Cu(In_1−xGa_x)Se₂ materials and devices with spectroscopic ellipsometry