On the Channel Hot-Electron's Interaction with C-Doped GaN Buffer and Resultant Gate Degradation in AlGaN/GaN HEMTs

Chaudhuri, RR and Joshi, V and Gupta, SD and Shrivastava, M (2021) On the Channel Hot-Electron's Interaction with C-Doped GaN Buffer and Resultant Gate Degradation in AlGaN/GaN HEMTs. In: IEEE Transactions on Electron Devices, 68 (10). pp. 4869-4876.

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Abstract

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.

Item Type:	Journal Article
Publication:	IEEE Transactions on Electron Devices
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to the Institute of Electrical and Electronics Engineers Inc.
Keywords:	AlGaN/GaN high electron mobility transistors (HEMTs); buffer traps; critical voltage; device design; electroluminescence. the (EL); gate leakage; hot electron; reliability
Department/Centre:	Division of Electrical Sciences > Electronic Systems Engineering (Formerly Centre for Electronic Design & Technology)
Date Deposited:	26 Nov 2023 08:23
Last Modified:	26 Nov 2023 08:23
URI:	https://eprints.iisc.ac.in/id/eprint/82930

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