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 $(1–2nm)$ ALD $Hf3N4$ or AlN layers exhibited well-behaved $C-V$ characteristics with an equivalent oxide thickness as low as $0.8nm$⁠, no significant flatband voltage shifts, and midgap density of interface states values of $2×1012cm−1eV−1$⁠. Functional $n$-channel and $p$-channel Ge field effect transistors with nitride interlayer/high-$κ$ oxide/metal gate stacks are demonstrated.