A Comparison of Intrinsic Point Defect Properties in Si and Ge
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1070-E06-05
A Comparison of Intrinsic Point Defect Properties in Si and Ge Jan Vanhellemont1, Piotr Spiewak2,3, Koji Sueoka4, Eddy Simoen5, and Igor Romandic6 1 Department of Solid State Sciences, Ghent University, Krijgslaan 281 S1, Ghent, Belgium 2 Materials Design Division, Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw, Poland 3 Umicore, Ludwiki 4, Warsaw, Poland 4 Department of System Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama, Japan 5 IMEC, Kapeldreef 75, Leuven, Belgium 6 Umicore EOM, Watertorenstraat 33, Olen, Belgium
ABSTRACT Intrinsic point defects determine to a large extent the semiconductor crystal quality both mechanically and electrically not only during crystal growth or when tuning polished wafer properties by thermal treatments, but also and not the least during device processing. Point defects play e.g. a crucial role in dopant diffusion and activation, in gettering processes and in extended lattice defect formation. Available experimental data and results of numerical calculation of the formation energy and diffusivity of the intrinsic point defects in Si and Ge are compared and discussed. Intrinsic point defect clustering is illustrated by defect formation during Czochralski crystal growth.
INTRODUCTION Intrinsic point defects determine to a large extent the semiconductor crystal quality both mechanically and electrically not only during crystal growth or when tuning polished wafer properties by thermal treatments, but also and not the least during device processing. They play a crucial role in dopant diffusion and activation, in gettering processes and in extended lattice defect formation. An in-depth knowledge of the point defects properties is therefore essential for successful defect engineering and process and yield control. Thanks to 50 years of intensive research, a huge database and know how is available for Si. For Ge the situation is less favourable as few (and mostly very old) experimental data exist for the vacancy [1 and references therein] and data are even lacking for the self-interstitial. Ge receives a lot of attention at the moment for its application as active layer in advanced devices in view of the much higher carrier mobility compared to Si and of its compatibility with Si processing. As it is often used as a thin epitaxial layer on the Si substrate, it is useful to compare (point) defect properties in both materials [2]. In the present paper, the available experimental data are compared with results of numerical calculation of the formation energy and diffusivity of the intrinsic point defects in Si and Ge [3,4]. Intrinsic point defect recombination and clustering are also discussed.
EXPERIMENTAL AND THEORETICAL ASSESSMENT OF INTRINSIC POINT DEFECT SOLUBILITY AND DIFFUSIVITY Experimental results for silicon In Si, the most reliable quantitative data on the solubility and diffusivity of intrinsic point defects were obtained on the basis of metal diffusion experiments on one hand and of intr
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