High-Mobility Ge pMOSFETs With Crystalline ZrO₂ Dielectric

High-mobility Ge pMOSFETs with crystalline ZrO ₂ gate dielectric are realized and compared against devices with O ₃ /ZrO ₂ , amorphous ZrO ₂ , and Al ₂ O ₃ /ZrO ₂ gate dielectrics. The crystallization of ZrO ₂ provides for significantly improved effective hole mobility ( $\boldsymbol {\mu }_{\textsf {eff}}$ ) and reduced capacitance equivalent thickness (CET), boosting the transistor drive current. An interfacial Al ₂ O ₃ passivation layer enhances $\boldsymbol {\mu }_{\textsf {eff}}$ but increases the CET. Passivation-free Ge pMOSFETs with 2.5-nm crystalline ZrO ₂ gate 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.