Crystallization of Si( 1-y )C y films by excimer laser annealing: characterization of the microstructure of the films
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Crystallization of Si(l-y)Cy films by excimer laser annealing: characterization of the microstructure of the films P. BOHER, M. STEHLE and J.L. STEHLE, SOPRA S.A., 26 rue Pierre Joigneaux, 92270 Bois-Colombes (France) E. FOGARASSY, J.J. GROB, A. GROB, D. MULLER, Laboratoire PHASE, UPR du CNRS N' 292, BP20, 67037 Strasbourg (France) ABSTRACT Epitaxial Si(l-y)Cy substitutional alloy layers are prepared on monocrystalline silicon substrates by carbon multiple energy ion implantation followed by XeCl excimer laser annealing on large surfaces. Structural analysis of the films before and after laser annealing are made very precisely using spectroscopic ellipsometry (SE), x-ray diffraction (XRD) and Rutherford backscattering (RBS) techniques. We show that annealing energy densities higher than 2J/cm 2 result in monocrystalline epitaxial layers with low quantity of defects. The lattice contraction due to the carbon inclusion increases with the implanted C concentration up to about 1.1%. For higher values a more complex behaviour is observed with partial (or total) relaxation of the layer and/or carbide formation.. INTRODUCTION The Si(1.x)Gex system has received considerable attention for applications in the field of optoelectronics and high speed heterojunction bipolar transistors. These applications require a very good control of composition and stress of the epitaxial layers. To reduce the layer stress, inclusion of carbon has been studied by different techniques like molecular beam epitaxy, chemical vapor deposition (1), implantation (2) or laser annealing after implantation (3-4). However, due to the formation of carbide precipitates, only two ways of preparation can be applied; the growth can be made at low temperature (
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