Silicon dioxide passivation of AlGaN/GaN HEMTs for high breakdown voltage

A new inductively coupled plasma-chemical vapor deposition (ICP-CVD) SiO2 passivation for high voltage switching AlGaN/GaN high electron mobility transistors (HEMTs) is proposed to increase the breakdown voltage and the forward drain current. AlGaN/GaN HEMTs are fabricated and measured before and after SiO2 passivation. The measured off-state breakdown voltage of SiO2 passivated device is 455 V, whereas that of the unpassivated device is 238 V. The surface leakage current of AlGaN/GaN HEMTs are decreased due to SiO2 passivation. The forward drain currents of SiO2 passivated devices are increased by 20 %similar to 35% because two-dimensional electron gas (2DEG) charge is increased and the electron injections to the surface traps are decreased. SiO2 passivation is more suitable for high voltage switching AlGaN/GaN HEMTs than Si3N4 passivation due to a high breakdown voltage and a low leakage current.