Dielectric property and conduction mechanism of ultrathin zirconium oxide films

Stoichiometric, uniform, amorphous ${\mathrm{ZrO}}_2$ films with an equivalent oxide thickness of ∼1.5 nm and a dielectric constant of ∼18 were deposited by an atomic layer controlled deposition process on silicon for potential applications in metal–oxide–semiconductor (MOS) devices. The conduction mechanism is identified as Schottky emission at low electric fields and as Poole–Frenkel emission at high electric fields. The MOS devices showed low leakage current, small hysteresis (<50 mV), and low interface state density ${\text{(∼2×10}}^{11}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{-2}}{\mathrm{ eV}}^{\text{−1}}\mathrm{).}$ Microdiffraction and high-resolution transmission electron microscopy showed a localized monoclinic phase of $\mathrm{\alpha -}{\mathrm{ZrO}}_2$ and an amorphous interfacial ${\mathrm{ZrSi}}_x{\mathrm{O}}_y$ layer which has a corresponding dielectric constant of 11.