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Thermodynamic pathway for the formation of SnSe and SnSe2 polycrystalline thin ...
Fernandes, P. A.; Sousa, M. G.; Salomé, P. M. P.; Leitão, J. P.; Cunha, A. F. daIn this work, tin selenide thin films (SnSex) were grown on soda lime glass substrates by selenization of dc magnetron sputtered Sn metallic precursors. Selenization was performed at maximum temperatures in the range 300 °C to 570 °C. The thickness and the composition of the films were analysed using step profilometry and energy dispersive spectroscopy, respectively. The films were structurally and optically in...
Admittance spectroscopy of Cu2ZnSnS4 based thin film solar cells
Fernandes, P. A.; Sartori, A. F.; Salomé, P. M. P.; Malaquias, J.; Cunha, A. F. da; Graça, M. P. F.; González, J. C.In this report, we propose an AC response equivalent circuit model to describe the admittance measurements of Cu2ZnSnS4 thin film solar cell grown by sulphurization of stacked metallic precursors. This circuit describes the contact resistances, the back contact, and the heterojunction with two trap levels. The study of the back contact resistance allowed the estimation of a back contact barrier of 246 meV. The ...
Growth and characterization of Cu2ZnSn(S,Se)4 thin films for solar cells
Salomé, P. M. P.; Malaquias, J.; Fernandes, P. A.; Ferreira, M. S.; Cunha, A. F. da; Leitão, J. P.; González, J. C.; Matinaga, F. M.Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with their band gap energies around 1.45 eV and 1.0 eV, respectively, can be used as the absorber layer in thin film solar cells. By using a mixture of both compounds, Cu2ZnSn(S,Se)4 (CZTSSe), a band gap tuning may be possible. The latter material has already shown promising results such as solar cell efficiencies up to 10.1%. In this work, CZTSSe thin films were grown in...
Photoluminescence and electrical study of fluctuating potentials in Cu2ZnSnS4-b...
Leitão, J. P.; Santos, N. M.; Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. da; González, J. C.; Ribeiro, G. M.; Matinaga, F. M.In this work, we investigated structural, morphological, electrical, and optical properties from a set of Cu2ZnSnS4 thin films grown by sulfurization of metallic precursors deposited on soda lime glass substrates coated with or without molybdenum. X-ray diffraction and Raman spectroscopy measurements revealed the formation of single-phase Cu2ZnSnS4 thin films. A good crystallinity and grain compactness of the f...
Study of optical and structural properties of Cu2ZnSnS4 thin films
Leitão, J. P.; Santos, N. M.; Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. da; González, J. C.; Matinaga, F. M.Cu2ZnSnS4 is a promising semiconductor to be used as absorber in thin film solar cells. In this work, we investigated optical and structural properties of Cu2ZnSnS4 thin films grown by sulphurization of metallic precursors deposited on soda lime glass substrates. The crystalline phases were studied by X-ray diffraction measurements showing the presence of only the Cu2ZnSnS4 phase. The studied films were copper ...
Assessment of the potential of tin sulphide thin films prepared by sulphurizati...
Malaquias, J.; Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. daIn this work, SnxSy thin films have been grown on soda-lime glass substrates by sulphurization of metallic precursors in a nitrogen plus sulphur vapour atmosphere. Different sulphurization temperatures were tested, ranging from 300 °C to 520 °C. The resulting phases were structurally investigated by X-Ray Diffraction and Raman spectroscopy. Composition was studied using Energy Dispersive Spectroscopy being then...
Study of polycrystalline Cu2ZnSnS4 films by Raman scattering
Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. daCu2ZnSnS4 (CZTS) is a p-type semiconductor that has been seen as a possible low-cost replacement for Cu(In,Ga)Se2 in thin film solar cells. So far compound has presented difficulties in its growth, mainly, because of the formation of secondary phases like ZnS, CuxSnSx+1, SnxSy, Cu2−xS and MoS2. X-ray diffraction analysis (XRD), which is mostly used for phase identification cannot resolve some of these phases fr...
A study of ternary Cu2SnS3 and Cu3SnS4 thin films prepared by sulfurizing stack...
Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. daThin films of Cu2SnS3 and Cu3SnS4 were grown by sulfurization of dc magnetron sputtered Sn–Cu metallic precursors in a S2 atmosphere. Different maximum sulfurization temperatures were tested which allowed the study of the Cu2SnS3 phase changes. For a temperature of 350 ◦C the films were composed of tetragonal (I -42m) Cu2SnS3. The films sulfurized at a maximum temperature of 400 ◦C presented a cubic (F-43m) Cu2...
Growth pressure dependence of Cu2ZnSnSe4 properties
Salomé, P. M. P.; Fernandes, P. A.; Cunha, A. F. da; Leitão, J. P.; Malaquias, J.; Weber, A.; González, J. C.; Silva, M. I. N. daIn this work, we show a set of growth conditions, for the two step process, with which the growth of CZTSe is successful and reproducible. The properties of the best CTZSe thin films grown by this method were examined by SEM/EDS, XRD, Raman scattering, AFM/EFM, transmittance and reflectance measurements, photoluminescence (PL) measurements and hot point probe. A broad emission band was observed in the photolumi...
Mo bilayer for thin film photovoltaics revisited
Salomé, P. M. P.; Malaquias, J.; Fernandes, P. A.; Cunha, A. F. daThin film solar cells based on Cu(In,Ga)Se2 as an absorber layer use Mo as the back contact. This metal is widely used in research and in industry but despite this, there are only a few published studies on the properties of Mo. Properties such as low resistivity and good adhesion to soda lime glass are hard to obtain at the same time. These properties are dependent on the deposition conditions and are associat...
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