435mS/mm transconductance for AlGaN/GaN HEMTs on HR-Si substrate with optimised gate-source spacing

A report is presented on high transconductance G_m measured on AlGaN/GaN HEMTs with a 12.5 nm-thick AlGaN barrier layer, grown on high resistivity silicon substrate using the MOCVD growth technique. 105 nm T-gate transistors were successfully fabricated using Pt/Ti/Pt/Au Schottky contact. Maximum current density of 723 mA/mm, current gain cutoff frequency of 80 GHz and maximum power gain cutoff frequency of 153 GHz are achieved. The devices feature a record peak extrinsic transconductance of 435 mS/mm which to the authors knowledge is the highest reported value for AlGaN/GaN HEMTs grown on Si (111). Different gate-source (L_gs) and drain-source (L_ds) spacing were also designed to study their influence on the electrical device characteristics. The devices were fabricated in the framework of a tight collaborative project between OMMIC and IEMN.