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Microwave Annealing of High Dose Al+-implanted 4H-SiC: Towards Device Fabrication


High-purity semi-insulating 8° off-axis 〈0001〉 4H-SiC was implanted with Al+ at different doses and energies to obtain a dopant concentration in the range of 5 × 1019–5 × 1020 cm−3. A custom-made microwave heating system was employed for post-implantation annealing at 2,000 °C for 30 s. Sheet resistance and Hall-effect measurements were performed in the temperature range of 150–700 K. At room temperature, for the highest Al concentration, a minimum resistivity of 3 × 10−2 Ω cm was obtained, whereas for the lowest Al concentration, the measured resistivity value was 4 × 10−1 Ω cm. The onset of impurity band conduction was observed at around room temperature for the samples implanted with Al concentrations ≥3 × 1020 cm−3. Vertical p +-i-n diodes whose anodes were made by 1.5 × 1020 cm−3 Al+ implantation and 2,000 °C/30 s microwave annealing showed exponential forward current–voltage characteristics with two different ideality factors under low current injection. A crossover point of the temperature coefficient of the diode resistance, from negative to positive values, was observed when the forward current entered the ohmic regime.

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The contributions of the clean room staff of CNR-IMM of Bologna is acknowledged; among them Fulvio Mancarella and Filippo Bonfè deserve a special mention for the processing of the 5 mm × 5 mm samples by conventional photolithography. We also acknowledge the contributions of: Mr. Salvatore Vantaggio of Parma University for the assistance in low-temperature Hall measurements, and Dr. Francesco Moscatelli for the electrical characterization of the p +-i-n diodes. This work is partially supported by the Army Research Office (ARO under contract No. W911NF-09-1-0407) and also by DARPA through the U.S. Naval Research Laboratory contract No. N0017310-2-C006.

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Correspondence to A. Nath or R. Nipoti.

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Nath, A., Rao, M.V., Tian, Y.L. et al. Microwave Annealing of High Dose Al+-implanted 4H-SiC: Towards Device Fabrication. Journal of Elec Materi 43, 843–849 (2014).

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  • Silicon carbide
  • p-type
  • ion implantation
  • doping
  • post-implantation annealing
  • p-i-n diodes
  • electrical characterization