Novel SiC Zener Diodes with High Operating Temperature of 300°C and High Power Density of 40 kW/cm²

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.

Avalanche Diodes with Low Temperature Dependence in 4H-SiC Suitable for Parallel Protection

“…So when the two mechanisms of breakdown are competitive, the temperature dependence of Zener diodes can reach to a very small value as the result in [2]. Since the breakdown voltage of the diodes presented is about three times higher than that in the Zener diodes having mixed avalanche-tunneling breakdown [1][2][3] and they have a positive temperature coefficient, we suggest that breakdown voltage is mainly due to avalanche breakdown. In comparison with mixed avalanche-tunneling breakdown Zener diodes in 4H-SiC which have the breakdown voltages of about 20 V, the advantage of pure avalanche breakdown diodes is that one can obtain intended breakdown voltage with comparable very low temperature dependence.…”

“…If these values of breakdown voltage are applied to Zener diodes in 4H-SiC which has a energy band gap of 3.26 eV, the breakdown voltage of a mixed avalanche-tunneling Zener diode can be in the range of about (13 V-20 V). 4H-SiC Zener diodes are indeed reported with breakdown voltages due to a mixed avalanche-tunneling breakdown of 23 V [1], 19 V [2], and 22 V [3]. Since the band gap in SiC decreases with increasing temperature [8], the breakdown voltage due to the tunneling effect has a negative temperature coefficient.…”

“…Thanks to its wide bandgap, high breakdown field, and high thermal conductivity, Zener diodes fabricated on 4H-SiC can operate at higher Zener voltages and higher temperatures than conventional Si-based Zener diodes. Some authors reported on 4H-SiC Zener diodes having mixed avalanche-Zener breakdown around 20 V [1][2][3]. Vassilevski et al presented a diode having pure avalanche breakdown of 280 V [4].…”

“…3 and Fig. 4, the breakdown voltage changes very slightly from 59 V to 60 V in the investigated range of temperature which corresponds to a ratio of ∆V/∆T = 3.7mV/K or a positive temperature coefficient γ of the breakdown voltage of 6.27 10 -5 K -1 calculated as follows:(1) Where Vz(T2) and Vz(T1) are the breakdown voltages measured at temperature T2 and T1 respectively.…”