Self-aligned Ge nMOSFETs with gate-last process on GeOI platform

We report the self-aligned Ge nMOSFETs with gate-last process on GeOI platform. Dummy gate was adopted to define the channel part, and source/drain part can be heavily doped, enabling the full cover of heavily doped area. Cyclic oxidation was used to reduce the Ge channel surface roughness, and AFM results indicated that the RMS for the final sample was down to 0.33nm. I-on/I-off ratio of 2.5 orders at V-g of 0.5V was obtained for the fabricated nMOSFET device, with channel length of Slim and channel width of 2 mu m. Electron mobility versus reverse charge curve results indicated that the Coulomb scattering centers degraded the I-on, thus further performance can be enhanced by optimizing the channel passivation process.