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Abstract 17 MeV proton irradiation at fluences from 3–7 × 1013cm−2of vertical geometry NiO/β-Ga2O3heterojunction rectifiers produced carrier removal rates in the range 120–150 cm−1in the drift region. The forward current density decreased by up to 2 orders of magnitude for the highest fluence, while the reverse leakage current increased by a factor of ∼20. Low-temperature annealing methods are of interest for mitigating radiation damage in such devices where thermal annealing is not feasible at the temperatures needed to remove defects. While thermal annealing has previously been shown to produce a limited recovery of the damage under these conditions, athermal annealing by minority carrier injection from NiO into the Ga2O3has not previously been attempted. Forward bias annealing produced an increase in forward current and a partial recovery of the proton-induced damage. Since the minority carrier diffusion length is 150–200 nm in proton irradiated Ga2O3, recombination-enhanced annealing of point defects cannot be the mechanism for this recovery, and we suggest that electron wind force annealing occurs.
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In Situ Transmission Electron Microscopy Observations of Forward Bias Degradation of Vertical Geometry β-Ga 2 O 3 Rectifiers
The microstructural changes and degradation under forward bias of verticalβ-Ga2O3rectifiers were observed by in-situ transmission electron microscopy. The devices show both a voltage dependence for the onset of visible degradation as well as a time dependence at this threshold voltage, suggesting a defect percolation process is occurring. The degraded rectifiers show a large decrease in forward current and different types of crystal defects are present, including stacking fault tetrahedra, microcracks, Ga-rich droplets and Au inclusions from the top electrode. Continued forward bias stressing is known to lead to macro-cracks oriented along the [010] crystal orientation and eventual delamination of the epitaxial drift layer, but this study is the first to provide insight into the appearance of the smaller defects that precede the large scale mechanical failure of the rectifiers. The initial stages of bias stressing also produce an increase in deep trap states near EC−1.2 eV.
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- Award ID(s):
- 1856662
- PAR ID:
- 10303524
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- ECS Journal of Solid State Science and Technology
- Volume:
- 9
- Issue:
- 5
- ISSN:
- 2162-8769
- Page Range / eLocation ID:
- Article No. 055008
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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