High-Mobility In0.23Ga0.77As Channel MOSFETs Grown on Ge/Si Virtual Substrate by MOCVD

We report high-mobility In_0.23Ga_0.77As channel MOSFETs grown on Ge/Si virtual substrate by metal-organic chemical vapor deposition for the first time. Through a low-temperature GaAs nucleation layer on Ge surface, a high-quality III-V MOSFET structure is obtained, with its etch pit density of 1.5 × 105 cm^-2. The maximum effective mobility is up to 1880 cm²/Vs, extracted by the split C-V method. The highest ON-current to the lowest OFF-current (ION/IOFF) ratio of ~2000 has been obtained. The 8-μm channel-length devices exhibit a drain current of 60 mA/mm and a peak extrinsic transconductance of 20 mS/mm. These results indicate that the high-mobility III-V nMOSFETs on Si substrate can be realized and even used to act as nMOSFETs for the fabrication of future CMOS.