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Publikācija: Improvement of CdS Film Optical Properties by Laser Radiation for Application in Solar Cells

Publication Type Conference paper
Funding for basic activity Unknown
Defending: ,
Publication language English (en)
Title in original language Improvement of CdS Film Optical Properties by Laser Radiation for Application in Solar Cells
Field of research 1. Natural sciences
Sub-field of research 1.3 Physical sciences
Authors Artūrs Medvids
Rimas Janeliukstis
Edvīns Daukšta
Pāvels Onufrijevs
José Luis Plaza
Sandra Rubio
Ernesto Diéguez
Igor Dmitruk
Natalia Berezovska
Keywords Laser, semiconductor
Abstract CdS plays an important role as a window layer forming n-CdS/p-CdTe heterojunction in photovoltaic cells based on CdTe. Closed space sublimation (CSS) technique is one of the main methods to form CdS layer. However, the polycrystalline layers formed by this method contain a lot of defects [1], which decrease lifetime of charge carriers. So, the aim of the work is to improve properties of CdS layer formed on ITO layer by CSS method using Nd:YAG laser radiation. The surface of CdS layer on ITO/glass structure was irradiated by pulsed Nd:YAG laser with different intensities. The measurements of topography by SEM after irradiation of the surface by laser showed micro-ripples formation. Two bands in photoluminescence (PL) spectra at 8 K were found – the red band at about 1.719 eV and the yellow band at 2.030 eV. Both bands correspond to donor – acceptor pair (DAP) recombination [2]. Laser irradiation caused a redistribution of intensities of these bands, which is explained by generation and recombination of intrinsic defects in DAP. A new intense PL band, containing two subbands, attributed to exciton bound to a neutral acceptor at ≈ 2.535 eV [2-3] and exciton, bound to a neutral donor at ≈ 2.540 eV [2-3] (at 1.6 K), appeared after irradiation by maximum laser intensity. Thermal quenching of PL band intensities was studied by determining defect activation energies. Activation energy of exciton band was found to be 38.9 ± 0.5 meV. After irradiation the intensity of Raman LO line increased about 3 times and phonon replica with energy of about 37 meV appeared. These facts indicate that our CdS film has crystallized and therefore, its quality has improved after irradiation by maximum laser intensity.
Hyperlink: http://fmnt.ut.ee/BookofAbstracts/FMNT-2013-Book-of-Abstracts.pdf 
Reference Medvids, A., Janeliukstis, R., Daukšta, E., Onufrijevs, P., Plaza, J., Rubio, S., Diéguez, E., Dmitruk, I., Berezovska, N. Improvement of CdS Film Optical Properties by Laser Radiation for Application in Solar Cells. In: Functional Materials and Nanotechnologies : International Conference FM&NT 2013: Book of Abstracts, Estonia, Tartu, 21-24 April, 2013. Tartu: 2013, pp.197-197.
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ID 16373