100 nm T-gate GaN-on-Si HEMTs Fabricated with CMOS-Compatible Metallization for Microwave and mm-Wave Applications

100 nm T-gate GaN-on-Si HEMTs fabricated using CMOS-compatible Au-free Ta/Al ohmic and Ti/Al gate contacts are reported in this work. The device exhibited a maximum drain current of 1.82 A/mm, a peak transconductance of 489 mS/mm, a cut-off frequency fT of 102 GHz, and a maximum oscillation frequency fmax of 114 GHz. Good RF performance comparable to their counterparts with Au-contained processes is achieved, demonstrating its potential for cost-effective microwave and mm-wave applications.

Introduction

GaN-on-Si HEMTs have attracted extensive attentions for microwave and mm-wave applications due to the advantages of large wafer size availability and the potential for mass production using CMOS foundries. Recently, significant improvement in the performance of GaN-on-Si have been realized with RF performance approaching that of GaN HEMTs on SiC [1]–[4]. In order to enable mass production with lower unit device cost, Si CMOS-compatible fabrication process is necessary to leverage on the mature silicon foundry production lines. However, there are still not many reports available on the GaN-on-Si microwave and mm-wave devices fabricated using CMOS-compatible process [5], [6]. In this work, we report 100-nm T-gate GaN-on-Si HEMTs fabricated with Si CMOS-compatible Ta/Al ohmic and Ti/Al gate contacts. The devices exhibit good RF performance rival other GaN HEMTs on Si realized using gold-based processes.