Negative Activation Energy of Gate Reliability in Schottky-Gate p-GaN HEMTs: Combined Gate Leakage Current Modeling and Spectral Electroluminescence Investigation

For the first time, we use electrical characterization, spectrally-resolved electroluminescence measurements and degradation tests to explain the negative activation energy of gate reliability in power GaN HEMTs with p-GaN Schottky gate. First, the origin of gate leakage current was modeled. The res...

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Bibliographic Details
Published in:	IEEE journal of the Electron Devices Society Vol. 12; pp. 703 - 709
Main Authors:	Fregolent, Manuel, Boito, Mirco, Disaro, Michele, De Santi, Carlo, Buffolo, Matteo, Canato, Eleonora, Gallo, Michele, Miccoli, Cristina, Rossetto, Isabella, Pizzo, Giansalvo, Russo, Alfio, Iucolano, Ferdinando, Meneghesso, Gaudenzio, Zanoni, Enrico, Meneghini, Matteo
Format:	Journal Article
Language:	English
Published:	New York IEEE 2024 The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:	Activation analysis Activation energy Aluminum gallium nitrides Bias Conduction model Current leakage Electrical properties Electroluminescence Electrons Failure analysis Gallium nitrides gate Leakage current HEMTs High electron mobility transistors High temperature Leakage current Leakage currents Logic gates MODFETs p-GaN HEMT Reliability Temperature dependence Thermionic emission Wide band gap semiconductors
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Summary:	For the first time, we use electrical characterization, spectrally-resolved electroluminescence measurements and degradation tests to explain the negative activation energy of gate reliability in power GaN HEMTs with p-GaN Schottky gate. First, the origin of gate leakage current was modeled. The results indicate that the gate leakage current originates from three different mechanisms: (i) thermionic emission of electrons from the uid-GaN layer across the AlGaN barrier, for gate voltages below threshold <inline-formula> <tex-math notation="LaTeX">(V_{G} \lt V_{TH}) </tex-math></inline-formula>, (ii) thermionic emission of electrons from the channel to the p-GaN layer <inline-formula> <tex-math notation="LaTeX">(V_{TH} \lt V_{G} \lt 4.5 V) </tex-math></inline-formula> and (iii) trap-assisted-tunneling of holes at the Schottky metal for higher gate voltages. Then, the analysis of the reliability as function of gate bias demonstrated a negative activation energy (longer lifetime at high temperature). By analyzing the electroluminescence spectra under high positive bias, the improved time to failure at high temperatures was ascribed to the increased hole injection and recombination, that reduces the overall number of electrons that undergo avalanche multiplication, leading to the breakdown. Finally, the model was validated by comparing the electrical properties and conduction model of the devices pre- and post-stress.
ISSN:	2168-6734 2168-6734
DOI:	10.1109/JEDS.2024.3454334