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Electrothermal Failure Physics of GaN Schottky Diodes Under High-Temperature Forward Biasing

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Pubblicato in:Micromachines vol. 16, no. 3 (2025), p. 242
Autore principale: Nahid Sultan Al-Mamun
Altri autori: Du, Yuxin, Song, Jianan, Chu, Rongming, Haque, Aman
Pubblicazione:
MDPI AG
Soggetti:
Silicon
Microelectromechanical systems
Sapphire
Bias
Chemical reactions
Semiconductors
Strain localization
Electric contacts
Misfit dislocations
Extreme environments
Intermetallic compounds
Degradation
Transistors
Thermal expansion
Defects
High temperature
Gold
Transmission electron microscopy
Diodes
Interdiffusion
Gallium nitrides
Temperature
Failure
Etching
Palladium
Schottky diodes
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Abstract: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.
ISSN:2072-666X
DOI:10.3390/mi16030242
Fonte:Engineering Database