A comparison study on the Al-based interfacial layers for Ge MIS devices

The performance of MIS devices on Ge substrate using AlN and Al₂O₃ as interfacial layer is investigated. Using AlN as interfacial layer can achieve lower leakage current and smaller hysteresis than using Al₂O₃ because AlN is a more effective barrier to against GeO volatilization and Ge diffusion. However, the interface state density of the AlN/Ge structure is poor. It is found that capping AlN on Al₂O₃ improves the hysteresis and leakage current while relax the interface state density degradation. It is suggested that appropriate AlN/Al₂O₃ stack can be used to fabricate high-quality MIS capacitor with ultra-thin effective oxide thickness.