Small- and Large-Signal Analyses of Different Low-Pressure-Chemical-Vapor-Deposition SiNx Passivations for Microwave GaN HEMTs
Journal article, 2018

Three types of SiN x passivation for microwave AlGaN/GaN HEMTs were deposited with low-pressure chemical vapor deposition under different deposition conditions, resulting in different silicon contents. The performance of the HEMTs is comprehensively investigated and compared. Both small- and large-signal analyses, such as generation-recombination (G-R) trap analysis, low-frequency noise characterization, and load-pull measurement, are indispensable to evaluate the effectiveness of a surface passivation. A Si-rich SiN x passivation shows excess G-R centers, whereas a Si-poor SiN x passivation exhibits significant current slump (30%). A bilayer SiN x passivation successfully shows not only a small current slump (9.7%) but also a suppressed G-R trapping/detrapping process. Moreover, the bilayer passivation demonstrates almost 2 orders of magnitude lower gate current noise spectra compared with the single-layer Si-rich SiN x passivation. The capacitance-voltage measurements reveal that the Si-rich SiN x layer removes the deep-level traps at the AlGaN/SiN x interface. Considering both small- and large-signal operations, it is concluded that the bilayer SiN x passivation is a suitable and versatile candidate for microwave GaN devices.

Capacitance-voltage (CV)


low-frequency dispersion

current collapse

low-frequency noise (LFN)


Tongde Huang

Nanjing University of Science and Technology

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Johan Bergsten

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Mattias Thorsell

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Niklas Rorsman

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics, Microwave Electronics

IEEE Transactions on Electron Devices

0018-9383 (ISSN)

Vol. 65 3 908-914

Subject Categories

Other Chemical Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering

Condensed Matter Physics



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