Abstract
Electrical characteristics of Ge pMOSFETs with HfO 2 , ZrO 2 , ZrO 2 /HfO 2 , and HfZrO x gate dielectrics are studied in this letter. A lower equivalent oxide thickness (EOT) is obtained in ZrO 2 device, which, however, has a higher interface trap density (D it ) due to its inferior dielectric/Ge interface. Interestingly, the D it and sub-threshold swing of Ge pMOSFETs are clearly reduced by ZrO 2 /HfO 2 stack gate dielectric. A peak hole mobility of 335 cm+ 2 /V-s is achieved in ZrO 2 /HfO 2 device thanks to good dielectric/Ge interface. Furthermore, the EOT of ZrO 2 /HfO 2 device is 0.62 nm, and the leakage current is 2× 10 -3 A/cm 2 . Therefore, a ZrO 2 /HfO 2 stack gate dielectric is promising for Ge MOSFETs.