The Au-mediated crystallization of a-Si:H has been investigated by in situ electrical measurements and scanning electron microscopy. The a-Si:H structure was prepared by evaporation of Au thin films of different thicknesses (50 - 600 Å ) onto intrinsic glow discharge deposited a-Si:H layers (≈ 5000 Å ). A rapid increase in the electrical resistance was associated to the nucleation and growth of Si crystals inside the Au film. The growth process promotes the accumulation of Au at the Si grain boundaries forming a metallic network. This network controls the electric resistance at the end of the crystallization reaction. The kinetics of transformation has been studied by isothermal treatments over the 140 - 180 °C temperature range. An activation energy of 2.1 eV was measured. An analysis of resistance data obtained by constant heating rate treatments suggest the rupture of the network interconnections at T ≥ 170 °C. SEM pictures showing the formation of Au clusters confirmed this suggestion.
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We would like to thank Dr. Markus Schubert for helpful discussions and Dr. Carlos Gatts for reviewing the manuscript. One of the authors (AAP) wishes to thank to the opportunity to have done part of his PhD work in the group of Prof. W. H. Bloss (IPE/Univ. Stuttgart). We also gratefully acknowledge financial support from brazilian (FINEP/CNPq/CAPES) and german (DAAD, Volkswagen-Stiftung) institutions.
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Pasa, A.A., Achete, C.A., Losch, W. et al. Characterization of Au-Mediated a-Si:H Crystallization by In Situ Electrical Measurements. MRS Online Proceedings Library 311, 105–110 (1993). https://doi.org/10.1557/PROC-311-105