Electrothermal Failure Physics of GaN Schottky Diodes Under High-Temperature Forward Biasing
The reliability of GaN-based devices operating under high temperatures is crucial for their application in extreme environments. To identify the fundamental mechanisms behind high-temperature degradation, we investigated GaN-on-sapphire Schottky barrier diodes (SBDs) under simultaneous heating and e...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Micromachines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-666X/16/3/242 |
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| Summary: | The reliability of GaN-based devices operating under high temperatures is crucial for their application in extreme environments. To identify the fundamental mechanisms behind high-temperature degradation, we investigated GaN-on-sapphire Schottky barrier diodes (SBDs) under simultaneous heating and electrical biasing. We observed the degradation mechanisms in situ inside a transmission electron microscope (TEM) using a custom-fabricated chip for simultaneous thermal and electrical control. The pristine device exhibited a high density of extended defects, primarily due to lattice mismatch and thermal expansion differences between the GaN and sapphire. TEM and STEM imaging, coupled with energy-dispersive X-ray spectroscopy (EDS), revealed the progressive degradation of the diode with increasing bias and temperature. At higher bias levels (4–5 V) and elevated temperatures (300–455 °C), the interdiffusion and alloying of the Au/Pd Schottky metal stack with GaN, along with defect generation near the interface, resulted in Schottky contact failure and catastrophic device degradation. A geometric phase analysis further identified strain localization and lattice distortions induced by thermal and electrical stresses, which facilitated diffusion pathways for rapid metal atom migration. These findings highlight that defect-mediated electrothermal degradation and interfacial chemical reactions are critical elements in the high-temperature failure physics of GaN Schottky diodes. |
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| ISSN: | 2072-666X |