Local epitaxial growth of ZrO2 on Ge (100) substrates by atomic layer epitaxy

High-$k$ dielectric deposition processes for gate dielectric preparation on Si surfaces usually result in the unavoidable and uncontrolled formation of a thin interfacial oxide layer. Atomic layer deposition of ∼55-Å ${\mathrm{ZrO}}_2$ film on a Ge (100) substrate using ${\mathrm{ZrCl}}_4$ and ${\mathrm{H}}_2\mathrm{O}$ at 300 °C was found to produce local epitaxial growth [(001) Ge//(001) ${\mathrm{ZrO}}_2$ and [100] Ge//[100] ${\mathrm{ZrO}}_2]$ without a distinct interfacial layer, unlike the situation observed when ${\mathrm{ZrO}}_2$ is deposited using the same method on Si. Relatively large lattice mismatch (∼10%) between ${\mathrm{ZrO}}_2$ and Ge produced a high areal density of interfacial misfit dislocations. Large hysteresis (>200 mV) and high frequency dispersion were observed in capacitance–voltage measurements due to the high density of interface states. However, a low leakage current density, comparable to values obtained on Si substrates, was observed with the same capacitance density regardless of the high defect density.