High-frequency AlGaN/GaN T-gate HEMTs on extreme low resistivity silicon substrates

Abstract

The T-gate high frequency AlGaN/GaN high electron mobility transistors (HEMTs) are demonstrated on an 8 inch extremely-low resistivity (ELR) silicon substrate with a resistivity of ∼2.5 mΩ cm to investigate the potential of using the ELR Si substrate for RF applications. The devices are also fabricated on the 60 Ω cm substrate for comparison. The 0.1 μm T-gate is realized by e-beam lithography to improve the high frequency characteristics of the devices. The short-circuit current gain cutoff frequency (fT), the maximum oscillation frequency (fmax), and maximum transconductance (gm,max) of 27 GHz, 71 GHz and 247 mS mm−1 can be achieved, respectively. The obtained high frequency performance is among the best reported to date for the GaN HEMTs on such low resistivity silicon substrates.