Effects of Ar+ etching of Cu2ZnSnSe4 thin films: An x-ray photoelectron spectroscopy and photoluminescence study
| Autor: | Jüri Krustok, Ian Forbes, M. V. Yakushev, O. M. Borodavchenko, V. D. Zhivulko, Robert W. Martin, J. Márquez-Prieto, M. A. Sulimov, M. V. Kuznetsov, A. V. Mudryi, Ekaterina Skidchenko, Paul R. Edwards |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
SEMICONDUCTING SELENIUM COMPOUNDS
Analytical chemistry F200 COPPER POTENTIAL FLUCTUATIONS 02 engineering and technology ENERGY DISPERSIVE X RAY ANALYSIS PHOTONS 01 natural sciences Spectral line Materials Chemistry SURFACE ELEMENTAL COMPOSITIONS Instrumentation PHOTOELECTRONS TEMPERATURE QC SELENIUM COMPOUNDS 010302 applied physics PRIMARY RADIATIONS 021001 nanoscience & nanotechnology Surfaces Coatings and Films Electronic Optical and Magnetic Materials DEEP ENERGY LEVELS X RAY DIFFRACTION ANALYSIS PHOTOLUMINESCENCE 0210 nano-technology Materials science Photoluminescence SEMICONDUCTING ZINC COMPOUNDS chemistry.chemical_element SEMICONDUCTING TIN COMPOUNDS ETCHING Ion X-ray photoelectron spectroscopy TIN COMPOUNDS THIN FILM SOLAR CELLS 0103 physical sciences THIN FILMS X RAY PHOTOELECTRON SPECTROSCOPY NONRADIATIVE RECOMBINATION CENTERS Electrical and Electronic Engineering Thin film business.industry Process Chemistry and Technology PHOTOLUMINESCENCE SPECTRUM Acceptor Copper Semiconductor chemistry business EXCITATION INTENSITY WAVELENGTH DISPERSIVE X-RAYS COPPER COMPOUNDS |
| Zdroj: | J. Vac. Sci. Technol. B. Nanotechnol. microelectron. Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics |
| ISSN: | 2166-2746 2166-2754 |
| Popis: | Cu2ZnSnSe4 (CZTSe) is a semiconductor used as the absorber layer in highly promising sustainable thin film solar cells. The authors study the effect of Ar+ etching of copper deficient and zinc excess CZTSe thin films deposited on Mo/glass substrates on the surface elemental composition, measured by x-ray photoelectron spectroscopy, and photoluminescence (PL) spectra. Low temperature PL spectra reveal a broad asymmetrical band at 0.95 eV. The temperature and excitation intensity dependencies of this band suggest that it is a free-to-bound (FB) recombination of electrons from the conduction band with holes localized at an acceptor affected by potential fluctuations. The surface composition of the as grown films demonstrates a strong copper deficiency: [Cu]/[Zn + Sn] = 0.33. The etching of the film surface using Ar+ beam increases [Cu]/[Zn + Sn] to 0.51, which is significantly smaller than that of 0.78 in the bulk, measured by wavelength dispersive x-ray analysis, demonstrating the presence on the surface of a copper-depleted layer. The Ar+ etching drastically reduces the FB band intensity by a factor of 4.5, broadens it and develops a low energy tail. Ar ions displace atoms in CZTSe lattice creating primary radiation defects, vacancies, and interstitials, which recombine at room temperature forming antisite defects with deep energy levels. Some of them generate the observed low energy tail and increase the mean depth of potential fluctuation γ, determined from the shape of the low energy side of FB band, from 24 meV before Ar+ etching to 35 meV after. Other deep defects work as nonradiative recombination centers reducing the intensity of the FB band. © 2018 Author(s). |
| Databáze: | OpenAIRE |
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