I. Rossetto¹, M. Meneghini¹, O. Hilt², E. Bahat-Treidel², C. De Santi¹, S. Dalcanale¹, J. Wuerfl², E. Zanoni¹, and G. Meneghesso¹

Published in:

IEEE Trans. Electron Devices, vol. 63, no. 6, pp. 2334-2339 (2016).

Abstract:

This paper reports an experimental demonstration of the time-dependent failure of GaN-on-Si power high-electron-mobility transistors with p-GaN gate, submitted to a forward gate stress. By means of combined dc, optical analysis, and 2-D simulations, we demonstrate the following original results: 1) when submitted to a positive voltage stress (in the range of 7-9 V), the transistors show a time-dependent failure, which leads to a sudden increase in the gate current; 2) the time-to-failure (TTF) is exponentially dependent on the stress voltage and Weibull-distributed; 3) the TTF depends on the initial gate leakage current, i.e., on the initial defectiveness of the devices; 4) during/after stress, the devices show a localized luminescence signal (hot spots); the spectral investigation mainly reveals a peak corresponding to yellow luminescence and a broadband related to bremsstrahlung radiation; and 5) 2-D simulations were carried out to clarify the origin of the degradation process. The results support the hypothesis that the electric field in the AlGaN has a negligible impact on the device failure; on the contrary, the electric field in the SiN and in the p-GaN gate can play an important role in favoring the failure, which is possibly due to a defect generation/percolation process.

Index Terms:

AlGaN/GaN high-electron-mobility transistor (HEMT), breakdown, emission microscopy, p-GaN gate.

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