Single Event Burnout Robustness Evaluation for β-Ga2O3 Vertical Schottky Barrier Diodes
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2025-07-11 |
| Journal | ECS Meeting Abstracts |
| Authors | Zhaowen He, Dongyang Li, Wei Ji, T. Paul Chow |
Abstract
Section titled “Abstract”Single-event burnout (SEB) induced by cosmic radiation poses a significant risk to wide bandgap (WBG) and extreme bandgap (EBG) semiconductor power devices in high altitude and space applications, as it can irreversibly destroy these devices thermally through mesoplasma formation originating from collapsing current filaments (microplasmas) prior to avalanche breakdown. Experimental [1] and simulation [2] studies have shown that SEB in commercially available vertical 4H-SiC power devices occurs at voltages less than half of the rated blocking voltage (BV rate ) under heavy-ion strikes, with bulk thermal conductivity identified as the primary determining factor. β-Ga 2 O 3 has emerged as a promising material for next-generation power devices due to its bandgap of 4.85eV and a high breakdown field of 8 to 10 MV/cm. However, its reliability in extreme radiation environment is expected to be limited due to its relatively low thermal conductivity of 9.5 Wm -1 K -1 [3]. In this work, we conduct a simulation-based robustness study to evaluate the ion induced SEB in β-Ga 2 O 3 vertical Schottky barrier diodes (VSBD). We perform electro-thermal transient simulations with adiabatic boundary condition using a 3-dimensional (3D) TCAD device simulator (Sentaurus) and the best-known material parameters. A Monte Carlo silver (Ag) ion collision model (1289MeV, LET(Si)=46.1MeV-cm 2 /mg) based on high fidelity radiation data in 4H-SiC from prior work [4] is used as the input of our simulation to predict SEB events under the assumption of equal ion induced electron-hole pair (EHP) generation in β-Ga 2 O 3 and 4H-SiC. In addition, ion-induced EHP generation is estimated for the same projectile species based on reported β-Ga 2 O 3 ionization energy and interpolated projection range for silver ion from the reported SRIM simulations [5] in literature, assuming equal projectile incident energy of 1289MeV. Estimated EHP generation and projection range from assumption two showing 18% and 39% reduction from assumption one respectively. Vertical heavy-ion strikes are performed at the anode side of VSBDs for various voltage ratings. A model of the thermal conductivity temperature dependence of each investigated semiconductor is used to model ion-induced thermal runaway. SEB failure is identified when the peak lattice temperature anywhere in the device exceeds the critical temperature of β-Ga 2 O 3 (2100K). The SEB threshold voltage (V SEB ) is defined as the minimum blocking voltage for which SEB occurs during a heavy-ion strike. The ratio of V SEB and BV rate provides the Figure of Merit (FoM) of device SEB robustness. Despite the difference in EHP generation and projection range, V SEB difference from two assumptions is less than 50V. The best SEB FoM for β-Ga 2 O 3 VSBD on a native substrate is limited to 0.13 for an 800V rated with a thin 3µm epitaxial layer and is improved to 0.22 by replacing to a diamond substrate due to enhanced substrate thermal conductivity. However, it decreases to 0.1 for devices above 5kV rating, exhibiting a negative correlation with rated voltage. Additionally, the observed improvement in FoM resulting from substrates with higher thermal conductivity diminishes for devices rated above 5 kV due to the increased thickness of the β-Ga₂O₃ epitaxial layer. In comparison, the SEB FoMs for 4H-SiC VSBDs are 0.41 to 0.24 across the investigated voltage ratings, aligning well with previously reported experimental data. β-Ga 2 O 3 SEB FoM is generally observed to be 58% to 68% lower compared to that of 4H-SiC, indicating a significant reduction in SEB robustness. Remarkably, the hot spot location in β-Ga 2 O 3 remains at the strike surface for all investigated voltage ratings due to its poor thermal conductivity, predicting failure location is at anode surface. Mesoplasma is pushed deeper into the epitaxial layer (about 3um deep from anode) for 4H-SiC VSBDs. In summary, this study examines the SEB robustness of β-Ga₂O₃ in comparison to 4H-SiC, revealing a more than 50% reduction in SEB FoM over all investigated rated voltages. Consequently, the findings suggest that the suitability of β-Ga₂O₃ for power device applications in radiation-intense environments may be significantly constrained. [1] J. M. Lauenstein et al., IEEE IRPS, 1 (2021). [2] J. A. McPherson et al., IEEE Trans. Nucl. Sci. 68 , 651 (2021). [3] P. Jiang et al., Appl. Phys. Lett. 113 , 232105 (2018). [4] P. J. Kowal et al., ANS RPSD 2018 (2018). [5] W. Ai et al., Jpn. J. Appl. Phys. 58 , 120914 (2019). [6] S. Yue et al., IEEE Trans. Electron Devices 71 , 7377 (2024). Figure 1