skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Investigation of carrier lifetime in 4H-SiC epilayers and lifetime control by electron irradiation

Abstract

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 lifetime control has been achieved.

Authors:
; ;  [1];  [2];  [2]
  1. Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
20971929
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 20; Other Information: DOI: 10.1063/1.2740580; (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; CARRIER LIFETIME; ELECTRON BEAMS; ELECTRONS; EPITAXY; IRRADIATION; MICROWAVE RADIATION; PHOTOCONDUCTIVITY; RECOMBINATION; SEMICONDUCTOR MATERIALS; SILICON COMPOUNDS

Citation Formats

Danno, Katsunori, Nakamura, Daisuke, Kimoto, Tsunenobu, Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan and Toyota Central R and D Laboratories, Inc, Aichi 480-1192, and Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510. Investigation of carrier lifetime in 4H-SiC epilayers and lifetime control by electron irradiation. United States: N. p., 2007. Web. doi:10.1063/1.2740580.
Danno, Katsunori, Nakamura, Daisuke, Kimoto, Tsunenobu, Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan and Toyota Central R and D Laboratories, Inc, Aichi 480-1192, & Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510. Investigation of carrier lifetime in 4H-SiC epilayers and lifetime control by electron irradiation. United States. doi:10.1063/1.2740580.
Danno, Katsunori, Nakamura, Daisuke, Kimoto, Tsunenobu, Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan and Toyota Central R and D Laboratories, Inc, Aichi 480-1192, and Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510. Mon . "Investigation of carrier lifetime in 4H-SiC epilayers and lifetime control by electron irradiation". United States. doi:10.1063/1.2740580.
@article{osti_20971929,
title = {Investigation of carrier lifetime in 4H-SiC epilayers and lifetime control by electron irradiation},
author = {Danno, Katsunori and Nakamura, Daisuke and Kimoto, Tsunenobu and Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan and Toyota Central R and D Laboratories, Inc, Aichi 480-1192 and Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510},
abstractNote = {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 lifetime control has been achieved.},
doi = {10.1063/1.2740580},
journal = {Applied Physics Letters},
number = 20,
volume = 90,
place = {United States},
year = {Mon May 14 00:00:00 EDT 2007},
month = {Mon May 14 00:00:00 EDT 2007}
}
  • 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
  • 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 thatmore » 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.« less
  • Topography image variation of threading edge dislocations (TEDs) in 4H-SiC epilayers has been investigated by grazing incidence high-resolution synchrotron topography. Six different images of TEDs resulting from an angle between the diffraction vector and the TED Burgers vector were confirmed by correlation between experimental topography images and simulation results. The TED-type distribution, dependent on the direction of the TED Burger vector, was examined on epitaxial wafers, while the spatial distribution of TEDs on a whole 2 in wafer along [1 1 2 0] and [1 1 0 0] was investigated.
  • Deep levels in n-type 4H-SiC epilayers have been investigated by deep level transient spectroscopy (DLTS). The Z{sub 1/2} and EH{sub 6/7} centers are dominant in as-grown samples. After electron irradiation at 116 keV, by which only carbon atoms may be displaced, the Z{sub 1/2} and EH{sub 6/7} concentrations are significantly increased. The Z{sub 1/2} and EH{sub 6/7} centers are stable up to 1500-1600 deg. C and their concentrations are decreased by annealing at 1600-1700 deg. C. In the irradiated samples, the trap concentrations of the Z{sub 1/2} and EH{sub 6/7} centers are increased with the 0.7 power of the electronmore » fluence. The concentrations of the Z{sub 1/2} and EH{sub 6/7} centers are very close to each other in all kinds of samples, as-grown, as-irradiated, and annealed ones, even though the condition of growth, irradiation (energy and fluence), and annealing has been changed. This result suggests that both Z{sub 1/2} and EH{sub 6/7} centers microscopically contain the same defect such as a carbon vacancy.« less