Atomic layer deposition of insulating nitride interfacial layers for germanium metal oxide semiconductor field effect transistors with high-κ oxide/tungsten nitride gate stacks

Atomic layer deposition (ALD) was used to deposit passivating interfacial nitride layers between Ge and high-κ oxides. High-κ oxides on Ge surfaces passivated by ultrathin (1–2 nm) ALD Hf₃N₄ or AlN layers exhibited well-behaved C-V characteristics with an equivalent oxide thickness as low as 0.8 nm, no significant flatband voltage shifts, and midgap density of interface states values of 2×10¹² cm^-1 eV^-1. Functional n-channel and p-channel Ge field effect transistors with nitride interlayer/high-κ oxide/metal gate stacks are demonstrated.