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

Abstract

We investigated characteristics of the Hf0.55Al0.45Ox MOS capacitor (HfAlO) under a high sweep voltage and positive bias stress (PBS). The role of a 0.5nm-thick HfO2 (HfO/HfAlO) or a 0.5nm-thick Al2O3 (AlO/HfAlO) interfacial layer (IL) between n-GaN and Hf0.55Al0.45Ox film on electrical properties was also discussed. The HfAlO, HfO/HfAlO and AlO/HfAlO capacitors showed a similar leakage current property. Each flatband voltage (Vfb) exhibited the same value against electric field (E) from Vfb. No Vfb hysteresis of all capacitors was observed at high Es from Vfb up to 3.5MVcm-1. Under PBS, the positive Vfb shift appeared in all capacitors and increased with increasing the E from Vfb. Note that the positive Vfb shift suppressed 0.3V regardless of IL even in high effective electric field from Vfb regions of 10~15MVcm-1 while the positive Vfb shift of the Al2O3 capacitor significantly increased above 0.5V at a low 6.5MVcm-1.