Germanium FETs and capacitors with rare earth CeO2/HfO2 gates

Long channel Ge FETs and capacitors with CeO2/HfO2/TiN gates were fabricated by photolithography and gate wet etch. Rare earth CeO2 in direct contact with Ge was used as a passivating layer producing lowest Dit values in the mid 1011 eV−1 cm−2 range. HfO2 cap reduces leakage and improves equivalent oxide thickness scaling of the whole gate stack. The p-FETs show exceptionally high ION/IOFF ratio ∼106, mainly due to low OFF current, and peak channel mobility around 80 cm2/V s. The n-FETs, although functional, show inferior performance producing ON currents an order of magnitude lower compared to p-FETs.