Sub-micron T-gate AlGaNGaN HEMTs Using Diluted ZEP520A

This study explores the development of sub-micron T-Gate AlGaN/GaN HEMTs using a diluted ZEP520A photoresist for controlling resist thickness. The three-layer photoresist of ZEP520A (1 : 1)/LOR5B/ZEP520A was designed, and a T-gate with 300 nm length was formed using electron beam lithography. The RF characteristics were measured using a GSG probe and exhibited the f
T
of 10 GHz and the f
max
of 17 GHz.