Implications of gate-edge electric field in AlGaN/GaN high electron mobility transistors during OFF-state degradation

• Published in: Microelectronics and reliability Vol. 54; no. 12; pp. 2650 - 2655
• Main Authors: Sun, H., Montes Bajo, M., Uren, M.J., Kuball, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: AlGaN/GaN high electron mobility transistor; Aluminum gallium nitrides; Applied sciences; Degradation; Electric field; Electric fields; Electroluminescence; Electronics; Exact sciences and technology; Gallium nitrides; Gate leakage; High electron mobility transistors; OFF-state stress; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Stresses; Surface defect; Surface defects; Transistors; Electroluminescence; Electric field; Gate leakage; Surface defect; OFF-state stress; AlGaN/GaN high electron mobility transistor; Ternary compound; Binary compound; Aluminium nitride; Numerical method; Failures; Gallium nitride; III-V compound; Degradation; Finite element method; High electron mobility transistor; Spatial distribution; Local field; High field; Damaging
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/j.microrel.2014.09.020

•We characterize the gate edge electric field in AlGaN/GaN HEMTs.•The field lowers at the generated failure sites upon off-state stress.•The areas without stress-induced defects are not affected during the degradation.•Electroluminescence can be used as a prescreening tool for device early failures. Gate degradation in high electron mobility transistors (HEMTs) under OFF-state stress results from the high electric field near the gate edge. We investigate the evolution of this field over time in AlGaN/GaN HEMTs upon OFF-state stress using a combination of electroluminescence (EL) microscopy and spectroscopy. EL analysis suggests that the electric field at the sites of generated surface defects is lowered after the stress, with greater lowering at higher stress temperature. The ON-state EL spectrum remains unchanged after the stress, suggesting that the regions without generated defects are not affected during the degradation. A finite element model is employed to further demonstrate the effect of surface defects on the local electric field. A correlation is observed for the spatial distribution of the EL intensity before and after the generation of leakage sites, which provides a prescreening method to predict possible early failures on a device.