High voltage GaN HEMT compact model: Experimental verification, field plate optimization and charge trapping

Abstract To improve the long-term stability of AlGaN/GaN HEMTs, the reduction of gate and drain leakage currents and electrical anomalies at pinch-off is required. As electron transport in these devices is both coupled with traps or surface states interactions and with polarization effects, the identification and localization of the preeminent leakage path is still challenging. This paper demonstrates that thermal laser stimulation (TLS) analysis (OBIRCh, TIVA, XIVA) performed on the die surface are efficient to localize leakage paths in GaN based HEMTs. The first part details specific parameters, such as laser scan speed, scan direction, wavelength, and laser power applied for leakage gate current paths identification. It compares results obtained with Visible_NIR electroluminescence analysis with the ones obtained by the TLS techniques on GaN HEMT structures. The second part describes some failure analysis case studies of AlGaN/GaN HEMT with field plate structure which were successful, thanks to the OBIRCh technique.

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A GaN-HEMT Compact Model Including Dynamic RDSon Effect for Power Electronics Converters

Energies ◽

10.3390/en14082092 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2092

Author(s):

Ke Li ◽

Paul Leonard Evans ◽

Christopher Mark Johnson ◽

Arnaud Videt ◽

Nadir Idir

Keyword(s):

Power Electronics ◽

Physical Model ◽

Order Reduction ◽

Power Converter ◽

Compact Model ◽

Voltage Source ◽

Power Losses ◽

Gan Hemt ◽

Operation Conditions ◽

Power Electronics Converters

In order to model GaN-HEMT switching transients and determine power losses, a compact model including dynamic RDSon effect is proposed herein. The model includes mathematical equations to represent device static and capacitance-voltage characteristics, and a behavioural voltage source, which includes multiple RC units to represent different time constants for trapping and detrapping effect from 100 ns to 100 s range. All the required parameters in the model can be obtained by fitting method using a datasheet or experimental characterisation results. The model is then implemented into our developed virtual prototyping software, where the device compact model is co-simulated with a parasitic inductance physical model to obtain the switching waveform. As model order reduction is applied in our software to resolve physical model, the device switching current and voltage waveform can be obtained in the range of minutes. By comparison with experimental measurements, the model is validated to accurately represent device switching transients as well as their spectrum in frequency domain until 100 MHz. In terms of dynamic RDSon value, the mismatch between the model and experimental results is within 10% under different power converter operation conditions in terms of switching frequencies and duty cycles, so designers can use this model to accurately obtain GaN-HEMT power losses due to trapping and detrapping effects for power electronics converters.

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