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Abstract(s)
Thin 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) Cu2SnS3 phase. On increasing
the temperature up to 520 ◦C, the Sn content of the layer decreased and orthorhombic (Pmn21)
Cu3SnS4 was formed. The phase identification and structural analysis were performed using
x-ray diffraction (XRD) and electron backscattered diffraction (EBSD) analysis. Raman
scattering analysis was also performed and a comparison with XRD and EBSD data allowed
the assignment of peaks at 336 and 351 cm−1 for tetragonal Cu2SnS3, 303 and 355 cm−1 for
cubic Cu2SnS3, and 318, 348 and 295 cm−1 for the Cu3SnS4 phase. Compositional analysis
was done using energy dispersive spectroscopy and induced coupled plasma analysis.
Scanning electron microscopy was used to study the morphology of the layers. Transmittance
and reflectance measurements permitted the estimation of absorbance and band gap. These
ternary compounds present a high absorbance value close to 104 cm−1. The estimated band
gap energy was 1.35 eV for tetragonal (I -42m) Cu2SnS3, 0.96 eV for cubic (F-43m) Cu2SnS3
and 1.60 eV for orthorhombic (Pmn21) Cu3SnS4. A hot point probe was used for the
determination of semiconductor conductivity type. The results show that all the samples are
p-type semiconductors. A four-point probe was used to obtain the resistivity of these samples.
The resistivities for tetragonal Cu2SnS3, cubic Cu2SnS3 and orthorhombic (Pmn21) Cu3SnS4
are 4.59 × 10−2 cm, 1.26 × 10−2 cm, 7.40 × 10−4 cm, respectively.
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IOP Science