Development of High-Frequency GaN HFETs for Millimeter-Wave Applications

Masataka HIGASHIWAKI  Takashi MIMURA  Toshiaki MATSUI  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.7   pp.984-988
Publication Date: 2008/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.7.984
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Heterostructure Microelectronics with TWHM 2007)
GaN,  heterostructure field-effect transistors (HFETs),  millimeter-wave,  

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This paper describes the device fabrication process and characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs) aimed for millimeter-wave applications. We developed three novel techniques to suppress short-channel effects and thereby enhance high-frequency device characteristics: high-Al-composition and thin AlGaN barrier layers, SiN passivation by catalytic chemical vapor deposition, and sub-100-nm Ti-based gates. The Al0.4Ga0.6N/GaN HFETs with a gate length of 30 nm had a maximum drain current density of 1.6 A/mm and a maximum transconductance of 402 mS/mm. The use of these techniques led to a current-gain cutoff frequency of 181 GHz and a maximum oscillation frequency of 186 GHz.