Gamma radiation on gallium nitride high electron mobility transistors at ON, OFF, and prestressed conditions

Abstract

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 RON 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.

Heavy ion irradiation induced failure of gallium nitride high electron mobility transistors: effects of in-situ biasing

“…The current density in the ON-mode device degrades two orders of magnitude after 0.1 dpa whereas the OFF-mode device completely loses its functionality. It suggests that ON mode operation is more tolerant to irradiation effects than OFF mode, probably due to a more extended annealing period by self-heating during the ON state, providing a way of self-recovery during irradiation [20]. Furthermore, the application of both drain and gate voltage during irradiation can lead to a modification in the behavior of trapped charges due to the presence of horizontal and vertical electric fields.…”

“…Gold heavy ions with mid-level energy (1.5 MeV) and 6.5 × 10 15 gold cm −2 fluence are shown to generate defect clusters that decrease saturation current by four orders of magnitude and cause loss of gate control [12]. Some studies claimed that the presence of an electric field has no impact on incoming ion radiation [19], whereas others show dissimilar behavior in transport properties between ON and OFF conditions [20][21][22][23][24]. Ionizing sources, such as X-ray and 60 Co, have been employed to evaluate the influence of irradiation at various bias conditions in HEMTs.…”

“…The study found that the magnitude of the effects varied significantly with applied bias during exposure and that a single worst-case bias condition cannot be defined for all varieties of AlGaN/GaN HEMTs. The lack of systematic research on heavy ion irradiation that takes into account the operating state of devices (ON or OFF state) during irradiation, which can substantially influence reliability and tolerance to incoming irradiation [20], is the primary motivation for this study.…”

Influence of electrical field on the susceptibility of gallium nitride transistors to proton irradiation

“…While some studies have suggested that the presence of an electric field does not affect incoming ion radiation [18], others have shown dissimilar behavior between ON and OFF conditions [27,[29][30][31][32]. To evaluate the influence of irradiation on HEMTs, ionizing sources such as x-rays and 60 Co have been employed under various bias conditions.…”

“…Charge buildup can also affect the incoming proton ions and may cause non uniform irradiation dose in the devices. There needs to be more systematic research on low-energy ion irradiation that considers the operating state of devices (ON or OFF state) during irradiation, which can significantly influence their reliability and tolerance to incoming irradiation [29]. In our prior investigation [33], we employed high-energy Au 4+ ions at 2.8 MeV to explore the ON and OFF states of the identical GaN HEMT structure utilized in this study.…”