Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Application of gallium nitride high-electron-mobility transistors (GaN HEMTs) to millimeter-wave power amplifiers requires gate length scaling below 150 nm: in order to control short-channel effects, the gate-to-channel distance must be decreased, and the device epitaxial structure has to be complet...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2024-03, Vol.71 (3), p.1-12
Main Authors: Zanoni, Enrico, Santi, Carlo De, Gao, Zhan, Buffolo, Matteo, Fornasier, Mirko, Saro, Marco, Pieri, Francesco De, Rampazzo, Fabiana, Meneghesso, Gaudenzio, Meneghini, Matteo, Zagni, Nicolo, Chini, Alessandro, Verzellesi, Giovanni
Format: Article
Language:English
Subjects:
Aluminum gallium nitride
Aluminum gallium nitrides
Barrier layers
Carrier density
Deep levels
Electric fields
electron device failure physics
Electron gas
Gallium nitride
gallium nitride high-electron-mobility transistors (GaN HEMT)
Gallium nitrides
HEMT scaling
HEMTs
High electron mobility transistors
Hot electrons
Leakage current
Logic gates
Microwave transistors
millimeter wave
Millimeter waves
Nitrogen
Power amplifiers
Reliability
Semiconductor devices
short-channel effects
Silicon
Wave power
Wide band gap semiconductors
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Summary:Application of gallium nitride high-electron-mobility transistors (GaN HEMTs) to millimeter-wave power amplifiers requires gate length scaling below 150 nm: in order to control short-channel effects, the gate-to-channel distance must be decreased, and the device epitaxial structure has to be completely redesigned. A high 2-D electron gas (2DEG) carrier density can be preserved even with a very thin top barrier layer by substituting AlGaN with AlN, InAl(Ga)N, or ScAlN. Moreover, to prevent interaction of hot electrons with compensating impurities and defects in the doped GaN buffer, the latter has to be separated from the channel by a back barrier. Other device designs consist in adopting a graded channel (which controls the electric field) or to adopt nitrogen-polar (N-polar) GaN growth (which decreases the distance between gate and channel, thus attenuating short-channel effects). The aim of this article is to review the various options for controlling short-channel effects, improve off-state characteristics, and reduce drain-source leakage current. Advantages and potential drawbacks of each proposed solution are analyzed in terms of current collapse (CC), dispersion effects, and reliability.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2023.3318564