Polarized Raman scattering analysis of Cu2ZnSnSe4 and Cu2ZnGeSe4 single crystals

Guc, Maxim; Levcenko, S.; Izquierdo-Roca, Víctor; Fontané, Xavier; Arushanov, E.; Pérez-Rodrı́guez, A.

doi:10.1063/1.4830028

Cited by 70 publications

(73 citation statements)

References 42 publications

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“…The band gap of these compounds is found to increase from ∼1.0 eV for Cu 2 ZnSnSe 4 (CZTSe) 8 to ∼1.4 eV for Cu 2 ZnGeSe 4 , 9,10 and both crystallize in the kesterite-type structure. 11,12 With synthesis of the solid solution CZTGeSe and tuning of the [Sn]/[Ge] ratio, the bandgap energy of the compounds can be varied almost linearly with composition. 10,13 This band-gap variation is expected to occur mainly by changes in the energy position of the conduction band minimum (CBM).…”

Section: Introductionmentioning

confidence: 99%

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

et al. 2017

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The selenization of metallic Cu−Zn−Sn−Ge precursors is a promising route for the fabrication of low-cost and efficient kesterite thin-film solar cells. Nowadays, efficiencies of kesterite solar cells are still below 13%. For Cu(In,Ga)Se 2 solar cells, the formation of compositional gradients along the depth of the absorber layer has been demonstrated to be a key requirement for producing thin-film solar cells with conversion efficiencies above the 22% level. No clear understanding has been reached so far about how to produce these gradients in an efficient manner for kesterite compounds, but among the possible candidates, Ge arises as one of the most promising ones. In the present work, we evaluate the potential of incorporating Ge in Cu 2 ZnSnSe 4 to produce compositional gradients in kesterites. Synchrotron-based in situ energydispersive X-ray diffraction and X-ray fluorescence have been used to study the selenization of Cu−Zn−Sn−Ge metallic precursors. We propose a reaction mechanism for the incorporation of Ge atoms into the kesterite lattice after the formation of Cu 2 ZnSnSe 4 . Electron microscopy reveals that the annealing process leads to Cu 2 Zn(Sn,Ge)Se 4 absorber layers with an increase of Ge content toward the back contact with independence of the original location of Ge in the precursor layer. The effect of the Ge gradient on the optoelectronic properties of the absorber layer has been evaluated with room-temperature cathodoluminescence. The implications of the results for the development of kesterite solar cells are discussed, with the aim of encouraging new synthesis routes for compositionally graded absorbers.

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Section: Introductionmentioning

confidence: 99%

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

et al. 2017

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“…2 shows a typical Raman spectrum measured on S3 CZTSe sample, together with its fitting with lorentzian curves. All the observed peaks can be interpreted and all Raman active modes can be assigned to those of CZTSe semiconductor 14 and no modes related to possible secondary phases were detected. The low values of the full width on the half maximum ($5 cm À1 for the most of the peaks) support the high crystalline quality of the grown samples observed in the XRD analysis.…”

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confidence: 99%

Spectroscopic ellipsometry study of Cu2ZnSnSe4 bulk crystals

León

Levcenko

Serna

et al. 2014

Applied Physics Letters

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Using spectroscopic ellipsometry we investigated and analyzed the pseudo-optical constants of Cu2ZnSnSe4 bulk crystals, grown by the Bridgman method, over 0.8–4.5 eV photon energy range. The structures found in the spectra of the complex pseudodielectric functions were associated to E0, E1A, and E1B interband transitions and were analyzed in frame of the Adachi's model. The interband transition parameters such as strength, threshold energy, and broadening were evaluated by using the simulated annealing algorithm. In addition, the pseudo-complex refractive index, extinction coefficient, absorption coefficient, and normal-incidence reflectivity were derived over 0.8–4.5 eV photon energy range.

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“…The position of each Raman peak with the symmetry assignment is presented in Table I, which also contains theoretical calculations 17 and previously reported experimental data. 18 The symmetry assignment of Raman modes was done by comparing the experimentally obtained frequencies with the reported references as well as applying the rules 13 for the mode behavior to polarization measurements preformed on this sample. It can be concluded that peak positions in Table I are in good agreement with the previous work.…”

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Influence of compositionally induced defects on the vibrational properties of device grade Cu2ZnSnSe4 absorbers for kesterite based solar cells

Dimitrievska

Fairbrother

Saucedo

et al. 2015

Applied Physics Letters

136

127

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This work presents a detailed analysis of the impact of compositionally induced defects on the vibrational properties of Cu2ZnSnSe4 absorbers for kesterite based solar cells. Systematic changes in the intensity of the E and B modes located around the 170, 220, and 250 cm-1 frequency regions, which involve mostly cation vibrations, were observed and analyzed in relation to the occurrence of different kinds of defect clusters involving VCu, ZnCu, ZnSn, CuZn, and SnZn point defects. Additional changes are also interpreted in terms of the appearance of SnSe, ZnSe, and CuSe-like contributions at the 185 and 250 cm-1 spectral regions, respectively. The sensitivity of the Raman measurements to the presence of these kinds of defects corroborates the potential of Raman scattering for point defect assessment in these systems. © 2015 AIP Publishing LLCPeer ReviewedPostprint (published version

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Polarized Raman scattering analysis of Cu2ZnSnSe4 and Cu2ZnGeSe4 single crystals

Cited by 70 publications

References 42 publications

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

Spectroscopic ellipsometry study of Cu2ZnSnSe4 bulk crystals

Influence of compositionally induced defects on the vibrational properties of device grade Cu2ZnSnSe4 absorbers for kesterite based solar cells

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