Hot-Carrier-Stress-Induced Degradation of 1 kV AlGaN/GaN HEMTs by Employing SiO2 Passivation

High-voltage AlGaN/GaN HEMTs (high-electron-mobility transistors) are fabricated by employing SiO₂ passivation and the degradation due to the hot carrier stress has been investigated. Our experimental result shows that the SiO₂ passivation of AlGaN/GaN HEMT successfully achieves the breakdown voltage of 1 kV without any field plate design. The pulsed I-V measurement for AlGaN/GaN HEMT shows that the SiO₂ passivation suppresses the frequency dispersion and decreases the on-resistance from 2.46 to 1.38 mOmega-cm². The hot carrier stress degrades the electric characteristics of AlGaN/GaN HEMT because the high field increases the trapping at the surface and the interface. However, the SiO₂ passivation of AlGaN/GaN HEMT decreases the surface trapping and 2DEG depletion during the hot carrier stress, so that a passivated device exhibits less degradation than an unpassivated one. After the hot carrier stress with V_DS=30 V and V_GS=10 V is applied to the device for 5times10⁴ sec, the SiO₂ passivation decreases the stress-induced degradation of forward drain current from 30.4 to 24.5 %.