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 %~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