A comparative study of C plus Al coimplantation and Al implantation in 4H- and 6H-SiC

Kiyoshi Tone, Jian H. Zhao

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Abstract

Coimplantation of equal concentrations of C and Al in 6H- and 4H-SIC has been investigated comparatively with implantation of Al alone in the Al concentration range of NAi-8xW19 to 2xl021 cm 3. C-A1 coimplantation at either room temperature (RT) or 600 °C, when implanted with NA.I > 1 x 1020 cm 3, gives improvements over Al alone implantation in the specific contact resistance pc of Al ohmic contacts on the implanted surfaces. The lowest median values of pc obtained are 3 x and 6 x 10 5 ficm2 for 6H- and 4H-SIC, respectively. In the mid to high 1020 cm 3 NA1 range, sheet resistivity of the p-type implanted layers are also reduced by the coimplantation at RT. Temperature-dependent Hall-effect measurements reveal the correlated trends in increased impurity-band conduction and high-temperature (>400 K) hole concentration. Implantation at 600 °C, by either coimplantation or Al alone implantation, degrades the electrical characteristics in the mid 1020 cm 3 NA.\ range, which implies that amorphization of as-implanted layers is necessary for effective activation of Al acceptors. It will be shown that C-A1 coimplantation at RT can produce p+-n diodes with low reverse leakage currents and high forward current capability as evidenced by the 110 A/cm2 forward current density at 2.8 V and 19 nA/cm2 leakage current density at -100 V for 4H-SIC p+-n diodes created by C-A1 coimplantation at RT.

Original languageEnglish (US)
Pages (from-to)612-619
Number of pages8
JournalIEEE Transactions on Electron Devices
Volume46
Issue number3
DOIs
Publication statusPublished - Dec 1 1999

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Keywords

  • Al
  • C
  • Hall effect
  • Ohmic contact
  • Semiconductor device doping
  • Semiconductor device ion implantation
  • Semiconductor diodes
  • Semiconductor materials measurements
  • SiC

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