Characteristics Comparison of Nanochannel GaN-on-Si and GaN-on-SiC HEMTs

A comparative investigation on device characteristics of GaN-on-Si and GaN-on-SiC high electron mobility transistors (HEMTs) fabricated with the gate lengths of 175, 150, and 125 nm is conducted. The device performance of the HEMTs is evaluated through DC current-voltage, small-signal, and large-signal measurements. The HEMTs with 125 nm gate length exhibit better characteristics than the HEMTs with other gate lengths. Besides, obvious increases of maximum transconductance (G m) , drain current density (J D ), on/off current ratio, cutoff frequency (f T ), maximum oscillation frequency (f max ), power gain, and power-added efficiency (PAE) are observed for GaN-on-SiC HEMTs as compared with those for the GaN-on-Si HEMTs. The GaN-on-SiC HEMT with a gate length of 125 nm delivers a maximum G m of 299 mS mm −1 , a J D larger than 1.1 A mm −1 , an on/off current ratio of 3.8 × 10 4 , a f T of 59.4 GHz, a fmax of 62.3 GHz, a power gain of 17.6 dB, and PAE of 63.8%, which make it promising for RF power amplifier application.