Interfacial and electrical properties of Al₂O₃/HfO₂ bilayer deposited by atomic layer deposition on GeON passivated germanium surface

The interfacial and electrical properties of HfO₂ (5 nm) and Al₂O₃ (3 nm)/HfO₂ (5 nm) high-k deposited on nitride passivated Ge (100) have been investigated. The XPS spectroscopy and HRTEM were used to study the chemical and interfacial properties of deposited thin films. The stack with only HfO₂ shows the suppressed electrical properties such as high value of EOT and density of interface traps. The C-V measurement shows the reduced frequency dispersion with small hysteresis after introduction of 3 nm Al₂O₃ between HfO₂ and Ge/GeON. Further, low EOT and D_it have been obtained for GeON/Al₂O₃/HfO₂ gate stack as compared to that of only HfO₂ stack. The obtained values of dielectric constant and leakage current density are of ∼24.18 and 1.6 × 10⁻⁶ A cm⁻² at 1 V gate bias, respectively for the stack with Al₂O₃. Overall, the 3 nm Al₂O₃ capping with GeON improves interfacial and electrical properties of Ge MOS devices.