Symmetry-dependence of electronic grain boundary properties in polycrystalline CuInSe2 thin films

Baier, Robert E.; Abou‐Ras, Daniel; Rissom, T.; Lux‐Steiner, Martha Ch.; Sadewasser, Sascha

doi:10.1063/1.3652915

Cited by 33 publications

(38 citation statements)

References 18 publications

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“…Moreover, the potential profile demonstrates that the S3 GB is charge neutral, because a potential dip or peak is not seen at the GB. This outcome is in accordance with the literature; S3 GBs have been reported as charge neutral due to the low defect density for this GB type [40][41][42]. In conclusion, our KPFM results suggest that the chemical fluctuations do not have an apparent effect on S3 GBs.…”

Section: Electron Backscatter Diffraction (Ebsd)supporting

confidence: 94%

Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy

Aguiar

Erkan²,

Pruzan³

et al. 2016

Physica Status Solidi (a)

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Kesterite Cu 2 ZnSn(S,Se) 4 (CZTSSe) is a sustainable material for thin-film photovoltaics with device efficiencies greater than 12% have been demonstrated. Despite similar crystal structure and polycrystalline film microstructures, there is widespread evidence for larger-amplitude potential and bandgap fluctuations in CZTS than in the analogous Cu(In,Ga)Se 2 (CIGSe) chalcopyrite material. This disorder is believed to account for a sizable part of the larger open-circuit voltage (V OC ) deficit in CZTS devices, yet the detailed origins and length scales of these fluctuations have not been fully elucidated. Herein, we present a transmission electron microscopy study focusing on composition variation within bulk multicrystals of CZTS grown by the travelling heater method (THM). In these slow-cooled, solution grown crystals we find direct evidence for spatial composition fluctuations of amplitude <1 at.% ($5 Â 10 20 cm À3) and thus, explainable by point defects. However, rather than being homogeneously-distributed we find a characteristic 20 nm length scale for these fluctuations, which sets a definite length scale for band gap and potential fluctuations. At S3 grain boundaries, we find no evidence of composition variation compared to the bulk. The finding highlights such variations reported at grain boundaries in polycrystalline thin-films are direct consequences of processing methods and not intrinsic properties of CZTS itself.

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Section: Electron Backscatter Diffraction (Ebsd)supporting

confidence: 94%

Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy

Aguiar

Erkan²,

Pruzan³

et al. 2016

Physica Status Solidi (a)

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“…23 In contrast to other studies, where only one type 9,10,12 or two types 11 of GBs were reported, we observed three types in total on the same sample surface. This observation is consistent with a recent study of Baier et al 24 conducted on a CuInSe 2 sample. Fig.…”

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confidence: 94%

Reevaluation of the beneficial effect of Cu(In,Ga)Se2 grain boundaries using Kelvin probe force microscopy

Zhang

Tang

Kiowski

et al. 2012

Applied Physics Letters

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Potential variations at grain boundaries are analyzed on the surface and on untreated cross sections of the absorber in a Cu(In,Ga)Se2 solar cell applying Kelvin probe force microscopy. We observe three different types of potential variations between grain boundaries (dip-, step-, or peak-shape). The potential variations on cross sections are smaller than that on surfaces. Since the properties of grain boundaries on cross sections can be expected to resemble more closely the ones buried in the bulk as those on absorber surfaces, it is important to interpret functionalities of grain boundaries based on observations on cross sections.

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“…It is a consistent result from all SEM [24][25][26][27][28] and SPM measurements 29,30 applied (in combination with EBSD) on grain boundaries in Cu(In,Ga)(S,Se) 2 thin films that most R3 (twin) boundaries do not exhibit substantial changes in the measured signals. Thus, most of these high-symmetrical types of grain boundaries are considered electrically inactive.…”

Section: Ebsd Combined With Other Scanning Microscopy Techniquessupporting

confidence: 60%

Electron Backscatter Diffraction: An Important Tool for Analyses of Structure–Property Relationships in Thin-Film Solar Cells

Abou‐Ras

Kavalakkatt

Nichterwitz

et al. 2013

JOM

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The present work gives an overview of the application of electron backscatter diffraction (EBSD) in the field of thin-film solar cells, which consist of stacks of polycrystalline layers on various rigid or flexible substrates. EBSD provides access to grain-size and local-orientation distributions, film textures, and grain-boundary types. By evaluation of the EBSD patterns within individual grains of the polycrystalline solar cell layers, microstrain distributions also can be obtained. These microstructural properties are of considerable interest for research and development of thin-film solar cells. Moreover, EBSD may be performed three-dimensionally, by alternating slicing of cross sections in a focused ion-beam machine and EBSD acquisition. To relate the microstructural properties to the electrical properties of individual layers as well as to the device performances of corresponding solar cells, EBSD can be combined with electron-beam-induced current and cathodoluminescence measurements and with various scanning-probe microscopy methods such as Kelvin-probe force, scanning spreading resistance, or scanning capacitance microscopy on identical specimen positions. Together with standard device characterization of thin-film solar cells, these scanning microscopy measurements provide the means for extensive analysis of structure-property relationships in solar-cell stacks with polycrystalline layers.

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Symmetry-dependence of electronic grain boundary properties in polycrystalline CuInSe2 thin films

Cited by 33 publications

References 18 publications

Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy

Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy

Reevaluation of the beneficial effect of Cu(In,Ga)Se2 grain boundaries using Kelvin probe force microscopy

Electron Backscatter Diffraction: An Important Tool for Analyses of Structure–Property Relationships in Thin-Film Solar Cells

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Symmetry-dependence of electronic grain boundary properties in polycrystalline CuInSe2 thin films

Cited by 33 publications

References 18 publications

Cation ratio fluctuations in Cu2ZnSnS4 at the 20 nm length scale investigated by analytical electron microscopy

Cation ratio fluctuations in Cu2ZnSnS4 at the 20 nm length scale investigated by analytical electron microscopy

Reevaluation of the beneficial effect of Cu(In,Ga)Se2 grain boundaries using Kelvin probe force microscopy

Electron Backscatter Diffraction: An Important Tool for Analyses of Structure–Property Relationships in Thin-Film Solar Cells

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Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy

Cation ratio fluctuations in Cu₂ZnSnS₄ at the 20 nm length scale investigated by analytical electron microscopy