Ge p-MOSFETs With Scaled ALD $\hbox {La}_{2} \hbox {O}_{3}/\hbox {ZrO}_{2}$ Gate Dielectrics

Dielectric thin films of La₂O₃/ZrO₂ deposited by atomic layer deposition (ALD) are investigated to be employed in Ge Schottky barrier p-MOSFETs. La₂O₃ is used as a thin passivation layer and is capped by atomic-layer-deposited ZrO₂ as a gate dielectric. As the gate contact TiN capped by W is applied, midgap-level trap densities of ~ 3-4 × 10¹² eV^-1 cm^-2 and subtreshold slopes down to 115-120 mV/dec are achieved. The devices show negative threshold voltages of -0.5 to -0.6 V, as well as peak hole mobility values of ~ 50-75 cm²/V · s. Equivalent oxide thickness (EOT) is reduced to 0.96 nm upon postmetallization annealing without degrading the interface properties. The results show the scaling potential of the ALD La₂O₃ interlayer capped with ZrO₂ gate dielectrics for the integration into sub-1-nm EOT Ge p-MOSFET devices.