In this work, we demonstrate the degradation behavior and physical mechanism of AlGaN/GaN high-electron-mobility transistors (HEMTs) under hot-electron stress in hydrogen and nitrogen atmosphere. According to the monitoring results, the trends of Ids values are completely different during the same hot-electron stress in two types of atmosphere. The Ids values of the devices in pure hydrogen (the purity is 99.999%) continue decreasing at first and then remain at a fixed value, whereas the Ids values of the devices in pure nitrogen (the purity is 99.999%) recover to the initial value after the instability during the heating section and then instantaneously drop to zero 18 h after the beginning of the experiment. Comparing current-voltage (I-V) characteristics before and after the hot-electron stress experiment in hydrogen atmosphere, we find the output current decreases, the threshold voltage shifts forward, the gate leakage current increases, the current collapse enhances, and the gate-lag characteristic becomes worse. Based on our previous research, it can be concluded that hot-electron effects rather than hydrogen effects are the primary cause of device degradation. Moreover, the degradation in hydrogen atmosphere is more severe than that in nitrogen atmosphere according to the monitoring results ofIds values. We believe that the hydrogen can exacerbate the hot-electron effects through maintaining the lower junction temperature because of its higher thermal conductivity. A COMSOL finite-element simulation has been done to explain the mechanism.

中文翻译：

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热电子应力下气氛对 AlGaN/GaN HEMT 电特性的影响


在这项工作中，我们展示了 AlGaN/GaN 高电子迁移率晶体管（HEMT）在氢和氮气氛中热电子应力下的退化行为和物理机制。监测结果表明，两种大气中相同热电子应力下Ids值的变化趋势完全不同。纯氢气（纯度为99.999%）中器件的Ids值先持续下降，然后保持在固定值，而纯氮气（纯度为99.999%）中器件的Ids值恢复到初始值加热段不稳定后，实验开始18小时后瞬间降至零。对比氢气氛热电子应力实验前后的电流-电压（IV）特性，我们发现输出电流减小，阈值电压前移，栅极漏电流增加，电流崩塌增强，栅极滞后特性变差。根据我们之前的研究，可以得出结论，热电子效应而不是氢效应是器件退化的主要原因。而且根据Ids值的监测结果，氢气气氛中的降解比氮气气氛中的降解更为严重。我们认为，由于氢具有较高的导热性，因此可以通过维持较低的结温来加剧热电子效应。通过 COMSOL 有限元模拟来解释该机制。