United States

We investigate the drift of threshold voltage (VTH) and on-resistance (RON) in p-GaN power HEMTs after being submitted to negative/positive gate stress. Negative (Positive) Gate Stress (NGS/PGS) was applied at a gate-to-source bias of |VNGS| = VPGS = 6 V up to a cumulative stress time of 8×103 s at room temperature. We found that during NGS both VTH and RON increased over stress time, whereas during PGS both parameters decreased and stabilized to the values prior to stress application. This symmetric behavior was maintained after 5 full NGS/PGS stress cycles, indicating the absence of permanent degradation. To further characterize the VTH and RON transients, the NGS/PGS stress cycles were repeated at different temperatures (T=30-105 °C). While VTH exhibited a strong Tdependence (EA ≈ 0.6 eV) during NGS, a negligible variation of the VTH transients with T was found during PGS (EA ≈ 0 eV). Instead, RON transients exhibited approximately the same Tdependence during both NGS and PGS (EA ≈ 0.3-0.4 eV).

IEEE WiPDA 2022

Symmetrical VTH/RON Drifts Due to Negative/Positive Gate Stress in p-GaN Power HEMTs

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 The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.
 
 **Topics of interest**
* Heteroepitaxial & Bulk Materials Growth
* Gate Dielectrics & Surface Passivation
* Device Structures & Fabrication Techniques
* Device Characterization & Modeling
* Very-High Efficiency Or Compact Converters
* Safe Operating Areas Of Wide Bandgap Devices, including Short Circuit, Spike, &Transient Tolerance
* Harsh Environment (High Temperature) Operation & Reliability
* Packaging Power Modules & ICs
* Gate Drive & Other Auxiliary Circuits
* High-Performance Passive Components
* Hard-Switched & Soft-Switched Application Analysis
* Applications in Renewable Energy & Energy Storage, Transportation, Industrial Drives, Grid Power Systems, Space and Aerospace
* Wide Bandgap System Design Philosophies & Strategies
* Radio Frequency (RF) GaN
* Technology Roadmap of Wide Bandgap Including Devices, Applications and Packaging

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The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.

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Peak Channel Temperature Determination for an AlGaN/GaN HEMT with Raman Thermography and MTTF Extraction for Long Term Reliability

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The same core device model is shown to accurately reproduce the current-voltage and capacitance-voltage characteristics of enhancement-mode GaN 100 V power transistors of various sizes. Using linear scaling, excellent agreement with measurements is achieved over an order of magnitude variation in total gate width. Fractional variation in onresistance is shown to decrease with increasing transistor size, with implications for integrated circuit-sized transistors where gate width decreases by up to 5 orders of magnitude.

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Advancement in Integration for GaN Power ICs

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Threshold Voltage Behavior and Short-Circuit Capability of p-Gate GaN HEMTs Depending on Drain- and Gate-Voltage Stress

To reduce global warming / human health impacts, governments around the globe have been committed to reduce greenhouse gas and pollutant emissions.  To achieve these goals, vehicles with internal combustion engines (ICEs) are being replaced at very fast pace by vehicles with electrified power trains, (e.g., battery-electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), fuel-cell electric vehicles (FCEVs), etc.) To offer electrified functions, many power-electronic (PE) modules are incorporated on these vehicles (e.g., traction inverters, DC/DC converters, on-board / off-board chargers, etc.)  In these PE modules, WBG devices have shown promising potentials replacing Si ones to achieve better performance, smaller footprints, lighter weights, etc.  However, from many view angles, many WBG products are working under higher stresses than the Si ones to deliver better performance, leading to concerns of lower long-term reliability / higher parameter drifts.  To convince automotive manufacturers / suppliers, WBG vendors should disclose the raw-wafer / epi-layer defect info (e.g., densities, failure mechanisms, long-term aging effects, etc.), quality assurance processes and qualification results, EOL screening processes and pass/fail criteria, production yields, test-to-failure data (e.g., Weibull charts, bath-tub curves), and actual field return results.  For comparison, Si experience will be shared in this presentation.

Symmetrical VTH/RON Drifts Due to Negative/Positive Gate Stress in p-GaN Power HEMTs

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Peak Channel Temperature Determination for an AlGaN/GaN HEMT with Raman Thermography and MTTF Extraction for Long Term Reliability

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