A single high-energy particle, of the kind found in space or around nuclear facilities, can strike a semiconductor device under high voltage and destroy it, leaving it inoperable. The phenomenon is called single-event burnout (SEB), and it has long been a challenge in designing power electronics for harsh radiation environments. Researchers could measure the voltage at which a device failed, but a unified explanation of the physics occurring inside the device has been hard to come by. A research team centered at North Carolina State University in the United States combined experiments and numerical simulations on aluminum nitride (AlN), an ultra-wide-bandgap semiconductor, to build an analytical model that explains how SEB occurs. The team also proposed a new way to compare the radiation tolerance of semiconductor materials: using electric field as the benchmark rather than voltage, which depends heavily on device design.
Comparing by Electric Field, Not Voltage, to Understand Radiation-Induced Device Failure
SEB is a sudden, irreversible failure that occurs when a heavy ion or other high-energy particle passes through a semiconductor device under high applied voltage. Even a single particle can cause severe structural damage inside the device, ending its function as an electronic component. Traditionally, SEB tolerance has been evaluated with a voltage threshold: how many volts a device can withstand.
However, the voltage a device can withstand depends not only on the properties of the semiconductor material but also on device design, including electrode placement and semiconductor layer thickness. Cristyan Quiñones, the corresponding author of the paper, who earned his Ph.D. at North Carolina State University, explained in the university's announcement that because device design determines the voltage a device can tolerate before SEB occurs, comparing different materials requires looking at electric field rather than voltage. Electric field is the potential difference per unit length, and it captures the electrical stress inside a semiconductor in a way voltage alone cannot.
The team therefore introduced a metric called the critical applied electric field at which SEB occurs. Using applied electric field instead of a structure-dependent voltage is intended to make it easier to compare SEB tolerance across different semiconductor materials. The energy a heavy ion deposits per unit distance as it passes through a material is known as linear energy transfer (LET). In the AlN diodes in this study, the SEB threshold also dropped as LET increased.
AlN Diodes Tolerate Electric Fields About an Order of Magnitude Higher Than Typical Semiconductors
The results were presented on July 21, 2026, at Session B-6 of NSREC, an international conference on radiation effects, and on November 5 were published in the peer-reviewed journal IEEE Transactions on Nuclear Science as "Single-event burnout of AlN diodes under heavy-ion irradiation." In addition to North Carolina State University, researchers from NASA's Goddard Space Flight Center and Adroit Materials took part. North Carolina State University announced the findings to the general public on November 12.
The team irradiated Schottky barrier diodes and p-n diodes made of AlN with heavy ions and measured the thresholds at which SEB occurred. In both types of device, the burnout threshold fell as ion LET increased, consistent with trends reported for other semiconductor materials. When evaluated using critical applied electric field, AlN was found to withstand electric fields roughly an order of magnitude higher than typical semiconductors. However, neither the university announcement nor the paper's abstract gives the absolute critical applied electric field values for the materials compared.
This comparison draws on the team's own AlN irradiation experiments and on previously reported SEB data for other semiconductor materials. Not all materials were measured with the same equipment and under the same conditions. The published abstract and university announcement also do not make clear the number of devices tested, ion species and energies, the specific LET range, fluence (the number of irradiating particles per unit area), measurement temperature, voltage application procedures, the device structures used for comparison, or measurement error ranges. These conditions matter for judging the reproducibility of the results and the accuracy of cross-material comparisons, and they will need to be checked in the full text of the paper.
Charge Separation Intensifies the Local Electric Field and Triggers Electron Avalanche
The team combined its AlN experimental results and existing data for other semiconductor materials with numerical simulation to build an analytical model describing the physical process behind SEB. According to the model, the trigger for destruction is the separation of charge generated by the heavy ion's passage and the resulting local increase in electric field.
First, when a heavy ion passes through a semiconductor, it generates charge carriers such as electrons and holes along its path. Because a high voltage is applied to the device, negatively charged electrons and positively charged holes move in opposite directions and are pulled apart. This charge separation changes the internal electric field distribution and produces a locally very strong field. When that field reaches a critical value, an electron avalanche (avalanche breakdown) occurs, in which accelerated electrons generate new charge carriers one after another. As a result, a large amount of energy is concentrated in a small region, and the device is destroyed.
The team believes SEB in simple vertical devices can be explained as conventional avalanche breakdown triggered by the separation of ion-generated charge. The resulting analytical model reproduced, with good accuracy, how the burnout threshold changes with LET for multiple semiconductor materials. Quiñones also cited as an achievement the ability to explain results observed in different materials and devices with a single model.
However, neither the paper's abstract nor the university announcement gives fit statistics, residuals, or prediction error ranges quantifying how well the model matches the experimental data. The electron avalanche process described is an explanation based on experimental results and an analytical model, not a direct observation of every microscopic step leading to destruction. The announcements available so far also do not include results from independent replication by other research groups.
How Does This Differ from Earlier AlN Research and Gallium Oxide Radiation Studies?
Research on wide-bandgap semiconductors, including AlN, has advanced in recent years toward higher breakdown voltages and improved radiation tolerance. However, the ordinary dielectric breakdown field and the SEB threshold under heavy-ion irradiation evaluate different physical phenomena. And even within SEB testing, voltage and electric field assess different things, so their values cannot be compared directly.
For example, a study of AlN p-n junction diodes reported in Applied Physics Letters in January 2026 showed strong electrical characteristics, including a reverse breakdown field of 8 MV/cm and a forward current density above 1 kA/cm². But these values were measured without irradiation and differ from the SEB threshold under heavy-ion irradiation examined in the present study.
Meanwhile, a study of β-Ga₂O₃ (gallium oxide) heterojunction barrier Schottky diodes published in IEEE Electron Device Letters in March 2025 reported an SEB withstand voltage above 1.4 kV and held the SEB degradation rate to 9.6%. That work improved SEB tolerance through device design, combining a deep trench structure, p-type nickel oxide (NiO), and a field-plate termination structure using high-permittivity barium titanate. Its goals and evaluation methods differ from those of the present AlN study, which introduced critical applied electric field as a metric suited to cross-material comparison.
The figures reported in these studies are summarized below.
| Material and device | Test conditions | Reported metric and result | What is evaluated |
|---|---|---|---|
| AlN Schottky barrier and p-n diodes (this study) | SEB testing under heavy-ion irradiation | Critical applied electric field about an order of magnitude higher than typical semiconductors; absolute value not given in the abstract or university announcement | Cross-material SEB tolerance comparison that reduces the influence of device design |
| AlN p-n junction diode (January 2026) | Electrical characterization without irradiation | Reverse breakdown field of 8 MV/cm; forward current density above 1 kA/cm² | Ordinary electrical breakdown tolerance |
| β-Ga₂O₃ heterojunction barrier Schottky diode (March 2025) | SEB testing under heavy-ion irradiation | SEB withstand voltage above 1.4 kV; SEB degradation rate of 9.6% | Improved SEB tolerance through device structure |
The 1.4 kV SEB withstand voltage, the 8 MV/cm non-irradiated breakdown field, and the critical applied electric field introduced in the AlN study were each measured or evaluated under different conditions. The distinguishing feature of this study is its attempt to use a common metric, electric field, to compare differences between materials that device-level performance figures alone make hard to see.
Toward Design Rules for Radiation-Hardened Semiconductors
Ramón Collazo, a professor in the Department of Materials Science and Engineering at North Carolina State University and a co-author of the paper, said that understanding the physical mechanism of SEB makes it possible to develop design rules that minimize radiation damage. Previously, the focus was on testing how much radiation a device could withstand, but if the process leading to destruction can be explained by a physical model, that knowledge can also be applied to material selection and device structure design. The team expects the model to help in designing electronic devices for radiation-affected environments such as nuclear power generation, space exploration, biomedical engineering, and fusion experiments.
What has been reported so far is heavy-ion irradiation of AlN diodes in the laboratory and the construction of an analytical model for simple vertical devices. Spaceflight testing, field operation in nuclear reactor environments, system-level qualification, and adoption in commercial radiation-hardened products have not been reported. Whether the model can be applied to complex integrated circuits, specialized device structures, and different radiation environments also remains to be verified. If independent replication that accounts for detailed experimental conditions and measurement errors, and validation on more complex device structures, move forward, the work could lead to concrete methods for predicting SEB and improving radiation tolerance at the design stage.