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Wide band-gap II-VI semiconductors for optoelectronic applications
|Elżbieta Guziewicz 1, Marek Godlewski 1,2, Krzysztof Kopalko 1, Andrzej Szczerbakow 1, Iwona A. Kowalik 1, Aleksandra M. Wojcik 1, Sergiey Yatsunienko 1, Wojciech Paszkowicz 1, Elżbieta Lusakowska 1|
1. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
II-VI semiconductors are prospective candidates for optoelectronic applications like white light emitters, elements of solar cells, transparent conductive layers or buffer thin films.
We discuss properties of selected II-VI thin films obtained by the method of Atomic Layer Deposition (ALD) for above mentioned applications.
We show results for monocrystalline films of sphalerite-type ZnSe grown on GaAs(100) substrates from elemental Zn and Se precursors. Due to color mixing of band edge and deep defect-related emissions these layers emit intensive white light. Depth-profiling Cathodoluminescence (CL) investigations indicate that green and red emissions come from disordered regions of the films, close to the ZnSe/GaAs interface. The chromaticity parameters (color perception) of light emitted from ZnSe/GaAs layers can be tuned by either regulating the appropriate accelerating voltage of electrons or current density of primary electrons in CL investigations. These make ZnSe thin films good candidates as white light sources.
Zinc oxide thin films may be used for solar cells as transparent electrodes as well as for blue/UV light emitting devices. We achieved extra-low temperature growth of this material using diethylzinc (DEZn), which is a volatile and reactive zinc precursor. We obtained polycrystalline ZnO layers of good quality as confirmed by X-ray diffraction. Photoluminescence (PL) of these films show strong emission of excitonic origin, which is observed even at room temperature.
Wurzite- and sphalerite-type ALD CdS films show crystalline structure, flat surfaces and good optical properties. Room temperature CL spectra are dominated by strong edge emission at 2.4 eV. Low temperature PL of wurzite-type CdS show a strong edge luminescence with decay times similar to those typically found for the best quality bulk CdS crystal.
The work was partly financed by grant number 1 P03B 015 29 of Ministry of Education and Science, Poland
Presentation: Invited at E-MRS Fall Meeting 2007, Symposium C, by Elżbieta Guziewicz
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 16:20 Revised: 2009-06-07 00:44