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Optoelectronic and spectroscopic characterization of vapour-transport grown Cu2ZnSnS4 single crystals
- Source :
- Ng, T M, Weller, M T, Kissling, G P, Peter, L M, Dale, P, Babbe, F, De Wild, J, Wenger, B, Snaith, H J & Lane, D 2017, ' Optoelectronic and spectroscopic characterization of vapour-transport grown Cu 2 ZnSnS 4 single crystals ', Journal of Materials Chemistry A, vol. 5, no. 3, pp. 1192-1200 . https://doi.org/10.1039/c6ta09817g, Journal of Materials Chemistry A, vol 5, iss 3
- Publication Year :
- 2017
-
Abstract
- Single crystals of Cu2ZnSnS4 (CZTS) have been grown by iodine vapor transport with and without addition of NaI. Crystals with tin-rich copper-poor and with zinc-rich copper-poor stoichiometries were obtained. The crystals were characterized by single crystal X-ray diffraction, energy-dispersive X-ray spectroscopy, photocurrent spectroscopy and electroreflectance spectroscopy using electrolyte contacts as well as by spectroscopic ellipsometry, Raman spectroscopy and photoluminescence spectroscopy (PL)/decay. Near-resonance Raman spectra indicate that the CZTS crystals adopt the kesterite structure with near-equilibrium residual disorder. The corrected external quantum efficiency of the p-type crystals measured by photocurrent spectroscopy approaches 100% close to the bandgap energy, indicating efficient carrier collection. The bandgap of the CZTS crystals estimated from the external quantum efficiency spectrum measured using an electrolyte contact was found to be 1.64-1.68 eV. An additional sub-bandgap photocurrent response (Urbach tail) was attributed to sub bandgap defect states. The room temperature PL of the crystals was attributed to radiative recombination via tail states, with lifetimes in the nanosecond range. At high excitation intensities, the PL spectrum also showed evidence of direct band to band transitions at ∼1.6 eV with a shorter decay time. Electrolyte electroreflectance spectra and spectra of the third derivative of the optical dielectric constant in the bandgap region were fitted to two optical transitions at 1.71 and 1.81 eV suggesting a larger valence band splitting than predicted theoretically. The high values of the EER broadening parameters (192 meV) indicate residual disorder consistent with the existence of tail states.
- Subjects :
- Photoluminescence
Materials science
Band gap
02 engineering and technology
engineering.material
010402 general chemistry
01 natural sciences
Macromolecular and Materials Chemistry
chemistry.chemical_compound
symbols.namesake
General Materials Science
Kesterite
CZTS
Spectroscopy
Photocurrent
Renewable Energy, Sustainability and the Environment
business.industry
Materials Engineering
General Chemistry
021001 nanoscience & nanotechnology
0104 chemical sciences
chemistry
engineering
symbols
Optoelectronics
Quantum efficiency
Interdisciplinary Engineering
0210 nano-technology
business
Raman spectroscopy
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Ng, T M, Weller, M T, Kissling, G P, Peter, L M, Dale, P, Babbe, F, De Wild, J, Wenger, B, Snaith, H J & Lane, D 2017, ' Optoelectronic and spectroscopic characterization of vapour-transport grown Cu 2 ZnSnS 4 single crystals ', Journal of Materials Chemistry A, vol. 5, no. 3, pp. 1192-1200 . https://doi.org/10.1039/c6ta09817g, Journal of Materials Chemistry A, vol 5, iss 3
- Accession number :
- edsair.doi.dedup.....5ca3ce52aafe21974b096d71fb36294e