Papers by Author: Ryosuke Ishii

Abstract: Zener voltages of the fabricated SiC Zener diodes with various nitrogen concentrations in the range from 7×1017 to 5×1019 cm-3 are 17 to 87 V, and decreased with an increase in the nitrogen concentration. Furthermore, in a chopper circuit using SiC Zener diodes for SiCGT gate protection, the commutated current decreases slowly even though cathode current falls rapidly, and the SiCGT gate is protected from surge voltage by SiC Zener diode. Moreover, the value of Zener voltage after the operation was the same as that before half bridge operation at 47 V.

Abstract: Forward voltage drops of carbon implanted and thermal oxidized pin diode with thick drift layer are investigated to evaluate the effect on the lifetime. The forward voltage drops of the carbon implanted and thermal oxidized pin diodes with drift layer of 120 μm thick were around 4.0 V. Furthermore, blocking characteristics of 4H-SiC pin diodes with mesa-JTE, which were fabricated on C-face and Si-face substrates, are also investigated. The breakdown voltages of pin diodes with 250 μm and 100 μm epitaxial layers are 17.1 kV and 10.9 kV, respectively.

Abstract: This paper reports on the achievement of high-power 4H-SiC Zener diodes which have a high-doped pn junction with a large active area of 4 mm x 4 mm. The temperature coefficient of the breakdown voltage is as small as 5.7x10-5 1/K (positive) in the temperature range 20-300°C. In addition, reverse power capabilities of 6.3 kW (40 kW/cm2) at 20°C and 6.0 kW (38 kW/cm2) at 300°C during rectangular pulsed power operation (tw = 1 ms) have been achieved without device failure.