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Thermodynamic pathway for the formation of SnSe and SnSe2 polycrystalline thin films by selenization of metal precursors
In this work, tin selenide thin films (SnSe x ) 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 us...
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| Published in: | CrystEngComm 2013-01, Vol.15 (47), p.1278-1286 |
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| Main Authors: | , , , , |
| Format: | Article |
| Language: | English |
| Subjects: | |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | In this work, tin selenide thin films (SnSe
x
) 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 investigated by X-ray diffraction, Raman spectroscopy and optical transmittance and reflectance measurements. X-Ray diffraction patterns suggest that for temperatures between 300 °C and 470 °C, the films are composed of the hexagonal-SnSe
2
phase. By increasing the temperature, the films selenized at maximum temperatures of 530 °C and 570 °C show orthorhombic-SnSe as the dominant phase with a preferential crystal orientation along the (400) crystallographic plane. Raman scattering analysis allowed the assignment of peaks at 119 cm
−1
and 185 cm
−1
to the hexagonal-SnSe
2
phase and those at 108 cm
−1
, 130 cm
−1
and 150 cm
−1
to the orthorhombic-SnSe phase. All samples presented traces of condensed amorphous Se with a characteristic Raman peak located at 255 cm
−1
. From optical measurements, the estimated band gap energies for hexagonal-SnSe
2
were close to 0.9 eV and 1.7 eV for indirect forbidden and direct transitions, respectively. The samples with the dominant orthorhombic-SnSe phase presented estimated band gap energies of 0.95 eV and 1.15 eV for indirect allowed and direct allowed transitions, respectively.
Reaction schematics of the SnSe and SnSe
2
growth for a) low selenization temperature profiles (300 °C → 470 °C) and for b) high selenization temperature profiles (530 °C → 570 °C). |
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| ISSN: | 1466-8033 1466-8033 |
| DOI: | 10.1039/c3ce41537f |