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 "HfO
₂
/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 HfO
₂
, thermally grown GeO
₂
and epitaxial-Si shells are used as interlayers. Devices with a GeO
₂
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
.