High-Mobility Ge pMOSFETs With Crystalline ZrO2 Dielectric

Abstract

High-mobility Ge pMOSFETs with crystalline ZrO2 gate dielectric are realized and compared against devices with O3/ZrO2, amorphous ZrO2, and Al2O3/ZrO2 gate dielectrics. The crystallization of ZrO2provides for significantly improved effective hole mobility ( $\boldsymbol {\mu }_{\textsf {eff}}$ ) and reduced capacitance equivalent thickness (CET), boosting the transistor drive current. An interfacial Al2O3 passivation layer enhances $\boldsymbol {\mu }_{\textsf {eff}}$ but increases the CET. Passivation-free Ge pMOSFETs with 2.5-nm crystalline ZrO2gate dielectric achieve a higher $\boldsymbol {\mu }_{\textsf {eff}}$ than previously reported unstrained Ge pMOSFETs with the CET below 1 nm, at a high inversion-layer charge density.