Positron/positronium annihilation in nanocrystalline silicon thin films
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Positron and positronium annihilation investigations were applied to nanocrystalline silicon (nc-Si) thin films, for the first time. The nc-Si thin films with average grain diameters of 3–5 nm show intense blue luminescence at room temperature. The nanometer-sized Si crystallites formed in amorphous Si (a-Si) matrix give rise to this luminescence. Very highS-parameters up to 0.62 were observed in the as-grown a-Si thin film suggesting positronium formation in the a-Si layer. The average lifetime of the positrons in the a-Si was determined to be about 520 ps. TheS-parameters dropped significantly to 0.53 by crystallization of the thin film at 800 °C for 10 seconds, which was almost the same to the value observed in bulk Si (100) substrate. Further crystallization from 60 seconds to 1 hour showed smaller change in theS-parameters than that from the a-Si to 10 seconds. The large change in theS-parameters due to the annealing might be caused by the formation of Si nanocrystallites in a-Si matrix suggesting that positron is a sensitive probe for structural investigations of the nc-Si materials.
KeywordsSilicon Physical Chemistry Crystallization Thin Film Inorganic Chemistry
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- 1.L. T. CANHAM, Appl. Phys. Lett., 57 (1990) 1046.Google Scholar
- 2.Y. ITOH, H. MURAKAMI, A. KINOSHITA, Appl. Phys. Lett., 63 (1993) 2798.Google Scholar
- 3.P. ASOKA-KUMAR, K. G. LYNN, D. O. WELCH, J. Appl. Phys., 76 (1994) 4935.Google Scholar
- 4.X. ZHAO, O. SCHOENFELD, J. KUSANO, Y. AOYAGI, T. SUGANO, Japan J. Appl. Phys. Lett., 33 (1994) L649.Google Scholar
- 5.X. ZHAO, O. SCHOENFELD, S. KOMURO, Y. AOYAGI, T. SUGANO, Phys. Rev., B50 (1994) 18654.Google Scholar
- 6.Y. J. HE, M. HASEGAWA, R. LEE, S. BERKO, D. ADLER, A.-L. JUNG, Phys. Rev., B33 (1986) 5924.Google Scholar
- 7.X. ZHAO, O. SCHOENFELD, Y. AOYAGI, T. SUGANO, J. Phys. D: Appl. Phys., 27 (1994) 1575.Google Scholar
- 8.Y. KOBAYASHI, I. KOJIMA, S. HISHITA, T. SUZUKI, E. ASARI, M. KITAJIMA, Phys Rev., B52 (1995) 823.Google Scholar
- 9.M. KWETE, D. SEGERS, M. DORIKENS, L. DORIKENS-VAMPRAET, P. CLAUWS, Phys. Stat. Sol., A122 (1990) 129.Google Scholar