Examination of growth kinetics of copper rich Cu(In,Ga)Se2-films using synchrotron energy dispersive X-ray diffractometry

Rissom, T.; Mainz, Roland; Kaufmann, Christian A.; Caballero, R.; Efimova, Varvara; Hoffmann, Volker; Schock, Hans‐Werner

doi:10.1016/j.solmat.2010.05.007

Cited by 12 publications

(9 citation statements)

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“…The results of the quantification were confirmed by means of XRF results (measuring the integral compositions of the Cu (In,Ga)Se 2 layer). The gradients of Ga and In in the layer show a good agreement with energy-dispersive X-ray diffraction [17] (see Section 13.5 for an introduction) and AES measurements (see Section 16.4.7). Figure 16.4 shows a system of Si layers on and SiC substrate acquired with continuous dc at 800 V and 6 mA on a VG9000 instrument with concentration distributions from part per billion range for impurities and doping elements together with matrix concentrations of Si and C. glass substrates from different CuInS 2 deposition runs.…”

Section: Glow Discharge-mass Spectroscopysupporting

confidence: 64%

Elemental Distribution Profiling of Thin Films for Solar Cells

Hoffmann

Klemm

Efimova

et al. 2011

Advanced Characterization Techniques for Thin Film Solar Cells

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The present chapter will give an overview about the techniques glow discharge-optical emission (GD-OES) and glow discharge-mass spectroscopy (GD-MS), secondary ion mass spectroscopy (SIMS) and sputtered neutral mass spectroscopy (SNMS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS), which are methods broadly available for depth-resolved information about the matrix and trace element concentrations in multilayer stacks as those used for thin-film solar cells. In addition, also energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope may be applied on fractured cross-section specimens of these multilayer stacks, providing a quick way of analyzing the spatial distribution of the matrix elements, which is why this technique is also included in this chapter.AES, XPS, SIMS, and SNMS have a good lateral resolution, and depth-resolved information may be obtained by the investigation either of cross-section specimens or (most simply) of a fractured surface (see Section 16.6.3.1). All of these methods are in general performed in combination with a sputtering process when aiming for depth-resolved elemental distribution analysis. Thereby, ions are accelerated toward the surface of the sample and collide with the atoms in the region near the surface. The resulting collision cascade leads to the emission of sample material from the surface and forms a more or less flat crater. While AES and XPS only use this process to expose the region of interest, SIMS and SNMS analyze the sputtered material. Because of practical reasons, different sputtering rates are employed at times, that is, fast sputtering for removing sample material and slow sputtering during the analysis.XPS, AES, and SIMS work under ultrahigh vacuum conditions and must be performed at high-acceleration voltages in order to obtain high sputtering yields. These techniques make use of a scanning ion beam for sputtering, which allows the discrimination of crater edge effects. For the SIMS analysis, only an electronically gated area is used for the analysis. Similarly, in AES and XPS measurements, only

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Section: Glow Discharge-mass Spectroscopysupporting

confidence: 64%

Elemental Distribution Profiling of Thin Films for Solar Cells

Hoffmann

Klemm

Efimova

et al. 2011

Advanced Characterization Techniques for Thin Film Solar Cells

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“…The evolution of elemental depth distributions during CuðIn;GaÞðS;SeÞ 2 film formation processes has been studied by several authors by interrupting the formation process and analyzing the depth distributions using ex situ methods such as energy-dispersive x-ray spectroscopy, 5 scanning auger spectroscopy, 6 secondary neutral mass spectrometry, 7 and glow discharge optical emission spectroscopy. 8 The suitability of ex situ grazing incidence x-ray fluorescence for the high-resolution determination of graded depth profiles in thin films has recently been investigated by Streeck et al 9 Although ex situ methods usually feature good spatial resolutions of depth distributions, a high time resolution is necessarily connected with time-consuming experimental effort, because a single process has to be performed for each point in time at which depth distributions are to be analyzed. Moreover, due to possible influences of the interruption procedure, it is usually unknown how well the state of a sample at room temperature represents the state at elevated temperatures when the process was interrupted.…”

Section: Introductionmentioning

confidence: 99%

In situ analysis of elemental depth distributions in thin films by combined evaluation of synchrotron x-ray fluorescence and diffraction

Mainz

2011

Journal of Applied Physics

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In this work we present a method for the in situ analysis of elemental depth distributions in thin films using a combined evaluation of synchrotron x-ray fluorescence and energy-dispersive x-ray diffraction signals. We recorded diffraction and fluorescence signals simultaneously during the reactive annealing of thin films. By means of the observed diffraction signals, the time evolution of phases in the thin films during the annealing processes can be determined. We utilized this phase information to parameterize the depth distributions of the elements in the films. The timedependent fluorescence signals were then taken to determine the parameters representing the parameterized depth distributions. For this latter step, we numerically calculated the fluorescence intensities for a given set of depth distributions. These calculations handle polychromatic excitation and arbitrary functions of depth distributions and take into account primary and secondary fluorescence. Influences of lateral non-uniformities of the films, as well as the accuracy limits of the method, are investigated. We apply the introduced method to analyze the evolution of elemental depth distributions and to quantify the kinetic parameters during a synthesis process of CuInS 2 thin films via the reactive annealing of Cu-In precursors in a sulfur atmosphere.

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“…The formation of CGSe is investigated in more detail by cross‐sectional SEM in Section 3.4. The decrease of the peak at the CGSe 112 position from A to C can be explained by In–Ga interdiffusion , whereas the increase of a new peak at slightly higher energies (D) compared to that of CGSe 112 and CISe 103 can be explained by the rise of CIGSe 103 caused by increasing cation ordering (see next section). The dashed vertical lines in Figure (c) represent expected positions for CIGSe 112 and 103 with [Ga]/([Ga] + [In]) ~0.1 and show that for (D), the small peak on the right‐hand side is in accordance with the expected position of the 103 reflection.…”

Section: Resultsmentioning

confidence: 96%

Time‐resolved investigation of Cu(In,Ga)Se₂ growth and Ga gradient formation during fast selenisation of metallic precursors

Mainz

Weber

Rodríguez-Alvarez

et al. 2014

Progress in Photovoltaics

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Ga segregation at the backside of Cu(In,Ga)Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu–In–Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real‐time synchrotron‐based X‐ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross‐sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In–Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu–In–Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In–Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga‐rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 min reached conversion efficiencies of up to 14.2 % (total area, without anti‐reflective coating). The evolution of the Cu(In,Ga)Se2 diffraction signals reveals that the minimum process time for high‐quality Cu(In,Ga)Se2 absorbers is limited by cation ordering rather than Se incorporation. Copyright © 2014 John Wiley & Sons, Ltd.

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Examination of growth kinetics of copper rich Cu(In,Ga)Se2-films using synchrotron energy dispersive X-ray diffractometry

Cited by 12 publications

References 9 publications

Elemental Distribution Profiling of Thin Films for Solar Cells

Elemental Distribution Profiling of Thin Films for Solar Cells

In situ analysis of elemental depth distributions in thin films by combined evaluation of synchrotron x-ray fluorescence and diffraction

Time‐resolved investigation of Cu(In,Ga)Se₂ growth and Ga gradient formation during fast selenisation of metallic precursors

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Examination of growth kinetics of copper rich Cu(In,Ga)Se2-films using synchrotron energy dispersive X-ray diffractometry

Cited by 12 publications

References 9 publications

Elemental Distribution Profiling of Thin Films for Solar Cells

Elemental Distribution Profiling of Thin Films for Solar Cells

In situ analysis of elemental depth distributions in thin films by combined evaluation of synchrotron x-ray fluorescence and diffraction

Time‐resolved investigation of Cu(In,Ga)Se2 growth and Ga gradient formation during fast selenisation of metallic precursors

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Time‐resolved investigation of Cu(In,Ga)Se₂ growth and Ga gradient formation during fast selenisation of metallic precursors