High-Mobility In<sub>0.23</sub>Ga<sub>0.77</sub>As Channel MOSFETs Grown on Ge/Si Virtual Substrate by MOCVD

Abstract

We report high-mobility In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.23</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.77</sub> As 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . The maximum effective mobility is up to 1880 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /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.