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Title: Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation

Abstract

The authors report a significant reduction in deep level defects and improvement of carrier lifetime in 4H-SiC material after carrying out carbon or silicon ion implantation into the shallow surface layer of 250 nm and subsequent annealing at 1600 deg. C or higher temperature. Reduction of Z{sub 1/2} and EH{sub 6/7} traps from 3x10{sup 13} cm{sup -3} to below the detection limit (5x10{sup 11} cm{sup -3}) was observed by deep level transient spectroscopy in the material 4 {mu}m underneath the implanted layer. Minority carrier lifetime almost doubled in the implanted samples compared to the unimplanted samples. The authors propose that the implanted layer acts as a source of carbon interstitials which indiffuse during annealing and accelerate annealing out of grown-in defects in the layer underneath the implanted region.

Authors:
;  [1]
  1. Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan)
Publication Date:
OSTI Identifier:
20971814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 6; Other Information: DOI: 10.1063/1.2472530; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CARBON; CARBON IONS; CARRIER LIFETIME; DEEP LEVEL TRANSIENT SPECTROSCOPY; EPITAXY; INTERSTITIALS; ION IMPLANTATION; LAYERS; SEMICONDUCTOR MATERIALS; SILICON; SILICON CARBIDES; SILICON IONS

Citation Formats

Storasta, Liutauras, and Tsuchida, Hidekazu. Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation. United States: N. p., 2007. Web. doi:10.1063/1.2472530.
Storasta, Liutauras, & Tsuchida, Hidekazu. Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation. United States. doi:10.1063/1.2472530.
Storasta, Liutauras, and Tsuchida, Hidekazu. Mon . "Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation". United States. doi:10.1063/1.2472530.
@article{osti_20971814,
title = {Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation},
author = {Storasta, Liutauras and Tsuchida, Hidekazu},
abstractNote = {The authors report a significant reduction in deep level defects and improvement of carrier lifetime in 4H-SiC material after carrying out carbon or silicon ion implantation into the shallow surface layer of 250 nm and subsequent annealing at 1600 deg. C or higher temperature. Reduction of Z{sub 1/2} and EH{sub 6/7} traps from 3x10{sup 13} cm{sup -3} to below the detection limit (5x10{sup 11} cm{sup -3}) was observed by deep level transient spectroscopy in the material 4 {mu}m underneath the implanted layer. Minority carrier lifetime almost doubled in the implanted samples compared to the unimplanted samples. The authors propose that the implanted layer acts as a source of carbon interstitials which indiffuse during annealing and accelerate annealing out of grown-in defects in the layer underneath the implanted region.},
doi = {10.1063/1.2472530},
journal = {Applied Physics Letters},
number = 6,
volume = 90,
place = {United States},
year = {Mon Feb 05 00:00:00 EST 2007},
month = {Mon Feb 05 00:00:00 EST 2007}
}
  • Carrier lifetimes in 4H-SiC epilayers are investigated by differential microwave photoconductivity decay measurements. When the Z{sub 1/2} concentration is higher than 10{sup 13} cm{sup -3}, the Z{sub 1/2} center works as a recombination center. In this case, carrier lifetimes show positive dependence on the injection level (number of irradiated photons). On the other hand, other recombination processes such as surface recombination limit the lifetime when the Z{sub 1/2} concentration is lower than 10{sup 13} cm{sup -3}. In this case, carrier lifetimes have decreased by increasing the injection level. By controlling the Z{sub 1/2} concentration by low-energy electron irradiation, the lifetimemore » control has been achieved.« less
  • Results of carrier lifetime studies in low-doped epitaxial 4H SiC layers are reported. The free carrier absorption (FCA) technique was applied to extract carrier lifetime parameters and their spatial distribution in a wide photoexcitation range. The FCA magnitude is shown to scale linearly with the photoinjected carrier concentration, while the absorption cross section increases according to a {lambda}{sup 4.4} law for near infrared wavelengths. High spatial resolution carrier lifetime mapping of large 4H SiC areas revealed features related to structural imperfections of epilayers. Finally, a density dependent fast lifetime component was observed at high injection levels and attributed to band-to-bandmore » Auger recombination. {copyright} {ital 1997 American Institute of Physics.}« less
  • This paper tests the gettering ability of sites created by He implantation in 4H-SiC while heating the sample or not, and their impact on carrier lifetime. The spatial distribution of implantation-induced defects (cavities, stacking faults and dislocations) is studied by transmission electron microscopy (TEM) and is compared to gold profiles performed by Rutherford Backscattering (RBS) in samples intentionally contaminated with gold. Minority carrier lifetimes are also measured with a specific set-up based on microwave photoconductivity decay ({mu}-PCD). Though gold atoms do not seem to be efficiently trapped by cavities, the presence of dislocations is of major importance to monitor goldmore » diffusion. Indeed, they can double both its level and its diffusion length in the bulk. Gold is assumed to diffuse faster along dislocation cores. Besides, the implantation-related defects are found to improve the carrier lifetime in the material, but the role of He{sup 2+} left in cavities remains to be investigated.« less
  • Contrarily to the case of n-type 4H-SiC, very little is known about the presence of minority carrier traps in p-type epilayers. In this study, we performed the electrical characterization of as-grown, electron irradiated, and thermally oxidized p-type 4H-SiC, by using minority carrier transient spectroscopy. Four minority carrier traps are reported in 1.6–2.3 eV energy range above the valence band edge (E{sub V}). Particular emphasis is given to the mid-gap minority carrier trap (EH{sub 6∕7}) and to its correlation to an energetically close mid-gap majority carrier trap (HK4)