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On the Channel Hot-Electron’s Interaction With C-Doped GaN Buffer and Resultant Gate Degradation in AlGaN/GaN HEMTs
IEEE Transactions on Electron Devices ( IF 3.1 ) Pub Date : 2021-08-12 , DOI: 10.1109/ted.2021.3102469
Rajarshi Roy Chaudhuri , Vipin Joshi , Sayak Dutta Gupta , Mayank Shrivastava

In this work, we report a critical semi- ON-state drain stress voltage above which the gate current increases significantly and degrades permanently in AlGaN/GaN high electron mobility transistors (HEMTs). The observed critical voltage was found to be channel field-dependent by analyzing devices with different field plate lengths and passivation thicknesses, along with different gate–drain distances. Besides field dependence, the critical voltage was found to be carrier energy dependent by comparing the performance of devices subjected to semi- ON-state stress with devices under OFF-state stress. Experimentation on HEMTs with different buffer carbon doping variations revealed the degradation phenomenon to be a function of carbon doping in the GaN buffer. Furthermore, detailed electric field and electron temperature analysis revealed the drain edge to be a hot spot in accelerating interaction of hot electrons with traps in the GaN buffer leading to gate current degradation. A mechanism based on hot electron–buffer trap interaction-induced thermoelastic stress buildup and subsequent defect formation in the GaN buffer is proposed to explain the observed performance degradations. Observations such as a significant rise in channel temperature and accumulation of mechanical stress in the GaN buffer validate the proposed mechanism. Finally, the processes responsible for degradation lead to catastrophic failure of the device for longer stress times by the formation of cracks and pits in the GaN buffer, as validated by the postfailure field emission scanning electron microscopy (FESEM) analysis.

中文翻译:

关于沟道热电子与掺杂 C 的 GaN 缓冲器的相互作用以及 AlGaN/GaN HEMT 中的栅极退化

在这项工作中,我们报告了一个临界半导通态漏极应力电压,高于该电压时,AlGaN/GaN 高电子迁移率晶体管 (HEMT) 中的栅极电流显着增加并永久退化。通过分析具有不同场板长度和钝化厚度以及不同栅漏距离的器件,发现观察到的临界电压与沟道场有关。除了场依赖性,通过比较经受半导通状态应力的器件与处于关断状态应力的器件的性能,发现临界电压与载流子能量有关。对具有不同缓冲碳掺杂变化的 HEMT 进行的实验表明,降解现象是 GaN 缓冲中碳掺杂的函数。此外,详细的电场和电子温度分析表明,漏极边缘是加速热电子与 GaN 缓冲器中陷阱相互作用的热点,导致栅极电流退化。提出了一种基于热电子 - 缓冲陷阱相互作用引起的热弹性应力积累和随后在 GaN 缓冲中形成缺陷的机制来解释观察到的性能下降。诸如沟道温度显着升高和 GaN 缓冲器中机械应力积累等观察结果验证了所提出的机制。最后,正如故障后场发射扫描电子显微镜 (FESEM) 分析所证实的那样,由于在 GaN 缓冲液中形成裂纹和凹坑,导致退化的过程会导致器件在更长的应力时间内发生灾难性故障。
更新日期:2021-09-24
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