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Radiation susceptibility of electronics has always been about probing electrical properties in either transient or time-accumulated phenomena. As the size and complexity of electronic chips or systems increase, detection of the most vulnerable regions becomes more time consuming and challenging. In this study, we hypothesize that localized mechanical stress, if overlapping electrically sensitive regions, can make electronic devices more susceptible to radiation. Accordingly, we develop an indirect technique to map mechanical and electrical hotspots to identify radiation-susceptible regions of the operational amplifier AD844 to ionizing radiation. Mechanical susceptibility is measured using pulsed thermal phase analysis via lock-in thermography and electrical biasing is used to identify electrically relevant regions. A composite score of electrical and mechanical sensitivity was constructed to serve as a metric for ionizing radiation susceptibility. Experimental results, compared against the literature, indicate effectiveness of the new technique in the rapid detection of radiation-vulnerable regions. The findings could be attractive for larger systems, for which traditional analysis would take —two to three orders of magnitude more time to complete. However, the indirect nature of the technique makes the study more approximate and in need for more consistency and validation efforts. 

In this work, we demonstrate the rejuvenation of Ti/4H-SiC Schottky barrier diodes after forward current-induced degradation, at room temperature and in a few seconds, by exploiting the physics of high-energy electron interactions with defects. The diodes were intentionally degraded to a 42% decrease in forward current and a 9% increase in leakage current through accelerated electrical stressing. The key feature of our proposed rejuvenation process is very high current density electrical pulsing with low frequency and duty cycle to suppress any temperature rise. The primary stimulus is, therefore, the electron wind force, which is derived from the loss of the momentum of the high energy electrons upon collision with the defects. Such defect-specific or “just in location” mobilization of atoms allows a significant decrease in defect concentration, which is not possible with conventional thermal annealing that requires higher temperatures and longer times. We show evidence of rejuvenation with additional improvement in leakage current (16%) and forward current (38%) beyond the pristine condition. Transmission electron microscopy, geometric phase analysis, Raman spectroscopy, and energy dispersive x-ray-spectroscopy reveal the enhancement of defects and interfaces. The ultrafast and room temperature process has the potential for rejuvenating electronic devices operating in high power and harsh environmental conditions. 

The wide bandgap semiconductors SiC and GaN are commercialized for power electronics and for visible to UV light-emitting diodes in the case of the GaN/InGaN/AlGaN materials system. For power electronics applications, SiC MOSFETs (metal–oxide–semiconductor field effect transistors) and rectifiers and GaN/AlGaN HEMTs and vertical rectifiers provide more efficient switching at high-power levels than do Si devices and are now being used in electric vehicles and their charging infrastructure. These devices also have applications in more electric aircraft and space missions where high temperatures and extreme environments are involved. In this review, their inherent radiation hardness, defined as the tolerance to total doses, is compared to Si devices. This is higher for the wide bandgap semiconductors, due in part to their larger threshold energies for creating defects (atomic bond strength) and more importantly due to their high rates of defect recombination. However, it is now increasingly recognized that heavy-ion-induced catastrophic single-event burnout in SiC and GaN power devices commonly occurs at voltages ∼50% of the rated values. The onset of ion-induced leakage occurs above critical power dissipation within the epitaxial regions at high linear energy transfer rates and high applied biases. The amount of power dissipated along the ion track determines the extent of the leakage current degradation. The net result is the carriers produced along the ion track undergo impact ionization and thermal runaway. Light-emitting devices do not suffer from this mechanism since they are forward-biased. Strain has also recently been identified as a parameter that affects radiation susceptibility of the wide bandgap devices. 

Strain localization in microelectronic devices commonly arises from device geometry, materials, and fabrication processing. In this study, we controllably relieve the local strain field of AlGaN/GaN HEMTs by milling micro-trenches underneath the channel and compare the device performance as a function of the relieved strain as well as radiation dosage. Micro-Raman results suggest that the trenches locally relax the strain in device layers, decreasing the 2DEG density and mobility. Intriguingly, such strain relaxation is shown to minimize the radiation damage, measured after 10 Mrads of 60 Co-gamma exposure. For example, a 6-trench device showed only ∼8% and ∼6% decrease in saturation drain current and maximum transconductance, respectively, compared to corresponding values of ∼15% and ∼30% in a no-trench device. Negative and positive threshold voltage shifts are observed in 6-trench and no-trench devices, respectively, after gamma radiation. We hypothesize that the extent of gamma radiation damage depends on the strain level in the devices. Thus, even though milling a trench decreases 2DEG mobility, such decrease under gamma radiation is far less in a 6-trench device (∼1.5%) compared to a no-trench device (∼20%) with higher built-in strain. 

Radiation damage in electronic devices is known to be influenced by physics, design, and materials system. Here, we report the effects of biasing state (such as ON and OFF) and pre-existing damage in GaN high electron mobility transistors exposed to γ radiation. Controlled and accelerated DC biasing was used to prestress the devices, which showed significant degradation in device characteristics compared to pristine devices under ON and OFF states after γ irradiation. The experiment is performed in situ for the ON-state to investigate transient effects during irradiation until the total dose reaches 10 Mrad. It shows that threshold voltage, maximum transconductance, and leakage current initially decrease with dosage but slowly converge to a steady value at higher doses. After 10 Mrad irradiation, the OFF-state device demonstrates larger R ON and one order of magnitude increased leakage current compared to the ON-state irradiated device. The micro-Raman study also confirms that the ON-state operation shows more radiation hardness than OFF and prestressed devices. Prestressed devices generate the highest threshold voltage shift from −2.85 to −2.49 V and two orders of magnitude higher leakage current with decreased saturation current after irradiation. These findings indicate that high electric fields during stressing can generate defects by modifying strain distribution, and higher defect density can not only create more charges during irradiation but also accelerate the diffusion process from the ionizing track to the nearest collector and consequently degrade device performances.