Abstract The ionizing radiation response of a kind of commercial n-channel VDMOSFETs irradiated without external electric field stress is investigated. The effects of total dose, dose rate and H2 ambient on the radiation response, and the post-irradiation annealing behaviors of the devices have been explored. The devices are degraded obviously after 1200 Gy (Si) γ radiation. No appreciable true dose rate effect (or Enhanced Low Dose Rate Sensitivity, ELDRS) has been observed in the tested devices. The small and irregular variations in performance degradation with dose rate are believed to come from the variability in the radiation response of the devices. In addition, the ambient of 100% H2 accelerates the total dose degradation of the devices. The γ radiation-induced performance degradation contains significantly negative shift of threshold voltage (Vth) and remarkable increase in off-state leakage current (Ileak), which are mainly caused by the increase in radiation-induced oxide-trapped charges. No obvious change in interface states is observed during the whole irradiation experiments and the annealing processes. The bias condition adopted in this work during irradiations is probably the reason for these unexpected phenomena. Furthermore, the annealing results indicate that the radiation-induced oxide-trapped charges seem to possess relatively stable properties, and could not be fully compensated or neutralized at room temperature (RT) or high temperatures, or under positive high electric field stress (PHEFS) of +70 V.

中文翻译：

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无电场应力辐照N沟道VDMOSFET的γ辐射效应研究

摘要 研究了一种商用n沟道VDMOSFET在无外部电场应力照射下的电离辐射响应。研究了总剂量、剂量率和 H2 环境对辐射响应的影响，以及器件的辐射后退火行为。器件在 1200 Gy (Si) γ 辐射后明显退化。在测试设备中没有观察到明显的真实剂量率效应（或增强的低剂量率灵敏度，ELDRS）。性能退化随剂量率的微小和不规则变化被认为来自设备辐射响应的可变性。此外，100% H2 的环境会加速器件的总剂量衰减。γ辐射引起的性能退化包括阈值电压（Vth）的显着负移和关态漏电流（Ileak）的显着增加，这主要是由辐射引起的氧化物俘获电荷的增加引起的。在整个辐照实验和退火过程中没有观察到界面态的明显变化。这项工作在辐照期间采用的偏置条件可能是这些意外现象的原因。此外，退火结果表明，辐射诱导的氧化物俘获电荷似乎具有相对稳定的特性，并且在室温（RT）或高温下或在正高电场应力（PHEFS）下无法完全补偿或中和+70 V。