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Formation and annihilation of carbon vacancies in 4H-SiC
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0002-8760-1137
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2016 (English)In: 16th International Conference on Silicon Carbide and Related Materials, ICSCRM 2015, Trans Tech Publications, 2016, 331-336 p.Conference paper (Refereed)
Abstract [en]

The carbon vacancy (VC) is a major point defect in high-purity 4H-SiC epitaxial layers limiting the minority charge carrier lifetime. In layers grown by chemical vapor deposition techniques, the VC concentration is typically in the range of 1012 cm-3 and after device processing at temperatures approaching 2000 °C, it can be enhanced by several orders of magnitude. In the present contribution, we show that the cooling rate after high-temperature processing has a profound influence on the resulting VC concentration where a slow rate promotes elimination of VC. Further, isochronal annealing of as-grown and as-oxidized epi-layers protected by a carbon-cap was undertaken between 800 °C and 1600 °C. The results reveal that thermodynamic equilibrium of VC is established rather rapidly at moderate temperatures, reaching a VC concentration of only a few times 1011 cm-3 after 40 min at 1500 °C. Hence, the concept of eliminating VC’s by annealing at moderate temperatures under C-rich equilibrium conditions shows great promise and enables reannealing of high-temperature processed wafers, in contrast to the procedures commonly used today to eliminate VC. In-diffusion of carbon interstitials and out-diffusion of VC’s are discussed as the kinetics processes establishing the thermodynamic equilibrium.

Place, publisher, year, edition, pages
Trans Tech Publications, 2016. 331-336 p.
Keyword [en]
Carbon vacancy, DLTS, Lifetime enhancement, Thermodynamic equilibrium, Carrier lifetime, Chemical vapor deposition, Deep level transient spectroscopy, Point defects, Silicon carbide, Silicon wafers, Thermodynamics, Vacancies, After high temperature, Diffusion of carbons, Equilibrium conditions, Isochronal annealing, Moderate temperature, Thermodynamic equilibria, Temperature
National Category
Materials Engineering
URN: urn:nbn:se:kth:diva-195540DOI: 10.4028/ 2-s2.0-84971497650ISBN: 9783035710427OAI: diva2:1045818
4 October 2015 through 9 October 2015

QC 20161110

Available from: 2016-11-10 Created: 2016-11-03 Last updated: 2016-11-10Bibliographically approved

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Hallén, Anders
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