Germanium Nanowire Metal-Oxide-Semiconductor Field-Effect Transistor Fabricated by Complementary-Metal-Oxide-Semiconductor-Compatible Process

This work presents a complementary metal-oxide-semiconductor-compatible top-down fabrication of Ge nanowires along with their integration into pMOSFETs with "HfO2/TaN" high-k/metal gate stacks. Lateral Ge wires down to 14 nm in diameter are achieved using a two-step dry etch process on a high-quality epitaxial Ge layer. To improve the interface quality between the Ge nanowire and the HfO2, thermally grown GeO2 and epitaxial-Si shells are used as interlayers. Devices with a GeO2 shell demonstrated excellent I-ON/I-OFF ratios (> 10(6)), whereas the epitaxial-Si shell was found to improve the field-effect mobility of the holes in Ge nanowires to 254 cm(2)V(-1) . s(-1).