Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 52 (2019)

Investigation of single event eﬀects observed in SiC-SBDs
Y. Nakada,∗1 E. Mizuta,∗1 S. Kuboyama,∗1 and H. Shindou∗1
Wide bandgap semiconductor devices such as GaN andSiC are attractive for next-generation satellites to reduce
the energy losses in high-power and high-frequency systems. Although Si remains the dominant material usedin space systems, there is now a strong demand for newand more eﬃcient devices. However, there are few reports about power-handling applications. For such use
in satellite power applications, the mechanisms of single
event eﬀects (SEEs) must be resolved at ﬁrst with someappropriate steps.
In this study, we report the results of evaluating SEEs
on SiC-Schottky barrier diodes (SiC-SBDs) for powerhandling applications. The ion species we used in theexperiment was 86 Kr, 1242 MeV. The ion range was
113 µm; LET was 27 MeV/(mg/cm2 ) at the device surface. Figure 1 shows the device structure. The SiCSBD in this study was a type of commercial oﬀ-the-shelf(COTS) 1200 V device.
It is known that the failure modes of SiC-SBDs are
separated into three regions as shown in Fig. 2.1) Region 1 is the non-destructive region where the collectedcharge is reproducibly measured with no damage. Region 2 is where there is a permanent increase in leakage
current and thus, we deﬁne “Region 2” as the permanent
damage region. Region 3 is deﬁned as the catastrophic
failure region where an SEE occurs. However, the causeof the transition from Region 1 to Region 2, and thento Region 3 has yet to be clariﬁed. We therefore focus
on the area of transition and discuss Region 1 and 2,
particularly in terms of experiments and simulation.
Figure 3 (left) shows the transition of the leakage current (Ir) at reverse bias condition after irradiation. InFig. 3 (left), Ir was shown not to increase up to 220 V
but increased above 240 V. We assume that the threshold between 220 V and 240 V is the area of transition
from Region 1 to Region 2. Figure 3 (right) shows theIr values at 220 V and 240 V during irradiation. Ir wasshown not to increase with Kr ﬂuence at 220 V but does
increase at 240 V.
Figure 4 shows the TCAD (technology computer-aideddesign) simulation results of one particle traversing in
SiC-SBD by ECORCE.2) The parameters of SiC-SBDs
that we used were obtained by measuring the electricalcharacteristics. A calculated point in Fig. 4 was an in6FKRWWN\FRQWDFW
1HSL
1VXE

2KPLFFRQWDFW

Fig. 1. Device structure.

Fig. 2. Characteristic regions obs-erved by heavy ion irradiations on SiC-SBDs.
∗1Research and Development Directorate, Japan Aerospace Exploration Agency

Fig. 3. Ir values at each voltage after irradiation (left) and increase of Ir during irradiation at 220 V and 240 V (right).

Fig. 4. TCAD simulation results of one particle traversing in
SiC-SBD. (Vr = 220 V; solid line/Vr = 240 V; dashed line).

cident point of particles, directly below the electrode.
In Fig. 4, at ﬁrst, a particle traverses in a device withelectron-hole pairs being generated and thus, the electric ﬁeld was enhanced further. Second, the total current (Itot) was increased. Finally, the increase in current
causes the temperature of the calculated point to rise.
Compared to Vr = 220 V, the temperature value at Vr =240 V was remarkably high and above the melting point(3000 K) of the SiC crystal. Thus, the temperature exceeding the melting point is assumed to be one owing todevice deterioration.
In these experiments, we evaluated the area of transition between the three regions. To assess the experimental data, we conducted TCAD simulation of single
event eﬀects. This simulation was available to observe
the electron behavior inside SiC-SBDs when one particle makes an incident on a device. On comparing thebefore and after data, we found a signiﬁcant diﬀerence
regarding temperature at the incident point of particles.
Although certain issues regarding the simulation parameters remain to be resolved, the ability to simulate thecauses of SEE deterioration for power devices is necessary. To resolve these eﬀects, additional experiments arerequired.
References

1) S. Kuboyama et al., IEEE Trans. 53, 6 (2006).
2) A. Michez et al., IEEE Trans. 62, 4 (2015).

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