(Invited) Characteristics of GaN/High-k Capacitors Under Positive Bias Stress

We investigated characteristics of the Hf 0.55 Al 0.45 O x MOS capacitor (HfAlO) under a high sweep voltage and positive bias stress (PBS). The role of a 0.5nm-thick HfO 2 (HfO/HfAlO) or a 0.5nm-thick Al 2 O 3 (AlO/HfAlO) interfacial layer (IL) between n-GaN and Hf 0.55 Al 0.45 O x film on electrical properties was also discussed. The HfAlO, HfO/HfAlO and AlO/HfAlO capacitors showed a similar leakage current property. Each flatband voltage (V fb ) exhibited the same value against electric field (E) from V fb . No V fb hysteresis of all capacitors was observed at high Es from V fb up to 3.5MVcm -1 . Under PBS, the positive V fb shift appeared in all capacitors and increased with increasing the E from V fb . Note that the positive V fb shift suppressed 0.3V regardless of IL even in high effective electric field from V fb regions of 10~15MVcm -1 while the positive V fb shift of the Al 2 O 3 capacitor significantly increased above 0.5V at a low 6.5MVcm -1 .