AlGaN/GaN Heterostructure Field-Effect Transistors with Current Gain Cut-off Frequency of 152 GHz on Sapphire Substrates
- 1 April 2005
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 44 (4L), L475
- https://doi.org/10.1143/jjap.44.l475
Abstract
AlGaN/GaN heterostructure field-effect transistors (HFETs) with a gate length (L G) of 60–250 nm were fabricated on a sapphire substrate. The HFET structure was grown by plasma-assisted molecular-beam epitaxy, and a 2-nm-thick SiN film was formed on the device surface by catalytic chemical vapor deposition. All of the HFETs showed outstanding DC device performance. They exhibited maximum drain current densities of 1.50–1.55 A/mm and extrinsic transconductances of 340–400 mS/mm. The 60-nm-gate HFET had a current gain cut-off frequency ( f T) of 152 GHz and a maximum oscillation frequency ( f max) of 173 GHz. To our knowledge, the f T and f max are the highest ever reported for GaN-based transistors. These superior high-frequency characteristics were achieved with a process using a thin and high-Al-content barrier layer, high-quality catalytic chemical vapor deposition (Cat-CVD) SiN passivation, and sub-0.1-µm gates defined by electron-beam lithography.Keywords
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