AlGaN/GaN Field Effect Transistor with Gate Recess Structure and HfO2 Gate Oxide

AlGaN/GaN based HfO2 MOSHEMT (metal oxide semiconductor high electron transistor) with different gate recess depth was simulate to demonstrate a successful normally-off operation of the transistor. Three types of the HEMT structures including a conventional HEMT, a gate-recessed HEMT with 3 nm thick AlGaN layer, and MIS-HEMT without AlGaN layer in the gate region. The conventional HEMT showed a normally-on characteristics with a drain current of 0.35 A at V-G= 0 V and V-DS =15 V. The recessed HEMT with 3 nm AlGaN layer exhibited a decreased drain current of 0.15 A under the same bias condition due to the decrease of electron concentration in 2DEG (2-dimensional electron gas) channel. For the last HEMT structure, distinctive normally-off behavior of the transistor was observed, and the turn-on voltage was shifted to 0 V.