Details

Autor(en) / Beteiligte

• Rossetto, I.
• Meneghini, M.
• Pandey, S.
• Gajda, M.
• Hurkx, G. A. M.
• Croon, J. A.
• Sonsky, J.
• Meneghesso, G.
• Zanoni, E.

Titel

Field-Related Failure of GaN-on-Si HEMTs: Dependence on Device Geometry and Passivation

Ist Teil von

• IEEE transactions on electron devices, 2017-01, Vol.64 (1), p.73-77

Ort / Verlag

New York: IEEE

Erscheinungsjahr

2017

Quelle

IEEE Electronic Library Online

Beschreibungen/Notizen

• This paper reports on an extensive analysis of the breakdown of GaN-based Schottky-gated HEMTs submitted to high-voltage stress. The analysis was carried out on transistors with different lengths of the drain-side gatehead (L GH ), corresponding to different levels of electric field across the SiN passivation. Based on dc measurements, 2-D simulations, and optical analysis, we demonstrate the following original results: 1) when submitted to high drain voltages (in the OFF-state ), the transistors can show catastrophic failure; 2) electroluminescence microscopy indicates the presence of hot-spots on the drain-side of the gate; 2-D simulations support the hypothesis that failure occurs in correspondence of the gate-head, on the drainside edge, where the electric field in the silicon nitride passivation has its maximum; 3) this hypothesis is confirmed by the results of transmission electron microscope failure analysis that demonstrate the generation of a leakage path between the gate metal and the channel, 4) and by the dependence of the destructive voltage on the L GH value. 5) in addition, we propose and demonstrate an approach for improving the reliability of the devices, i.e., using a graded SiN passivation with increased thickness. The results described in this paper provide important information for the device optimization of Schottky-gated HEMTs.