High ε gate dielectrics Gd2O3 and Y2O3 for silicon

Abstract

We report on growth and characterization of both epitaxial and amorphous films ${\mathrm{Gd}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ of $\text{(ε=14)}$ and ${\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_3\text{(ε=18)}$ as the gate dielectrics for Si prepared by ultrahigh vacuum vapor deposition. The use of vicinal Si (100) substrates is key to the growth of (110) oriented, single-domain films in the ${\mathrm{Mn}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ structure. Typical electrical leakage results are ${10}^{\text{−3}} {\mathrm{A/cm}}^{\mathrm{2}}$ at 1 V for single domain epitaxial ${\mathrm{Gd}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ and ${\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ films with an equivalent ${\mathrm{SiO}}_{\mathrm{2}}$ thickness, $t_{\mathrm{eq}}$ of 15 Å, and ${10}^{\text{−6}} {\mathrm{A/cm}}^{\mathrm{2}}$ at 1 V for smooth amorphous ${\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ films $\text{(ε=18)}$ with a $t_{\mathrm{eq}}$ of only 10 Å. For all the ${\mathrm{Gd}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ films, the absence of ${\mathrm{SiO}}_{\mathrm{2}}$ segregation at the interface is established from infrared absorption measurements.