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

Abstract

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 (Gm), drain current density (JD), on/off current ratio, cutoff frequency (fT), maximum oscillation frequency (fmax), 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 Gm of 299 mS mm−1, a JD larger than 1.1 A mm−1, an on/off current ratio of 3.8 × 104, a fT 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.