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Photoluminescence of ZnO films studied by femptosecond sapphire:Ti laser

George V. Lashkarev 1Vitalii A. Karpyna 1Volodymyr Khranovskyy 1Vasyl Lazorenko 1Ivan V. Blonsky 2Igor Dmitruk 2Petro I. Korenyuk 2Volodymyr A. Baturin 3Alexander Karpenko 3Alexander G. Ulyashin 4Marek Godlewski 5

1. Frantsevich Institute for Problems of Materials Science (IPMS), 3, Krzhizhanivsky Str., Kiev 03680, Ukraine
2. Institute of Physics, National Academy of Sciences, Prospekt Nauki 46, Kyiv 03650, Ukraine
3. Institute of Applied Physics, NAS Ukraine, 58 Petropavlovskaya Str., Sumy 40030, Ukraine
4. University of Oslo, Physics Department and Centre for Materials Science and Nanotechnology, N-0316 Oslo, Blindern, Oslo N-0316, Norway
5. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland

Abstract

ZnO films were deposited by PEMOCVD, magnetron sputtering (MS) and reactive thermal evaporation on Al2O3 (0001), SiO2/Si (100) and SiNx/Si. Photoluminescence (PL) of as-grown and annealed ZnO films were studied at room temperature in range 350-800 nm by femptosecond sapphire:Ti laser (37 mW, 170 fs, 76 MHz). Annealing of ZnO films was carried out in air at 600-1000oC during 2-9 h.
As-grown ZnO films deposited by PEMOCVD on SiNx/Si were revealed the most intense near band edge (NBE) photoluminesense peaked at 3.27 eV. ZnO films deposited on SiO2/Si (100) and Al2O3 (0001) were characterized both NBE and broad deep-level luminescence. Annealing of samples results in significant decreasing of NBE PL. At the same time the deep-level luminescence at 2.39 eV sufficiently increases. It was revealed the influence of ZnO texture on PL intensity of films deposited by MS. The most intense PL was observed in samples with c-axis situated in plane of Al2O3 substrate. Annealing the samples also results in suppression of NBE PL.
Obtained results can be explained by oxygen diffusion through film-substrate interface during processes of growth and annealing, increasing of stresses in films at annealing as a result of large misfit between ZnO and Al2O3 substrates in periods of crystal lattice and thermal expansion coefficients.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium F, by George V. Lashkarev
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-16 09:17
Revised:   2009-06-07 00:44