High-Performance Germanium p- and n-MOSFETs With NiGe Source/Drain

In this paper, we report Ge pand n-channel metal- oxide-semiconductor field-effect transistors (MOSFETs) with NiGe source/drain (S/D) with high performance and low leakage current. The forward/reverse current ratio of the NiGe/n-Ge and NiGe/p-Ge junctions were ~10
⁵
and ~2 × 10
⁴
at |V| = ±1 V, respectively. Interface state densities Dit of Al
₂
O
₃
/GeO
₂
/Ge stack is improved to be around 10
¹²
/eV
^-1
cm
²
near the midgap after forming gas annealing; the gate-stack also shows excellent reliability under constant field stressing. Both p- and n-channel MOSFETs show sufficiently high I
_ON
/I
_OFF
ratio. High driving current of ~9 and ~4 μA/μm at |V
_GS
- V
_T
| = ±0.8 V and |V
_DS
| = ± V is obtained, respectively, for pand n-MOSFETs. Moreover, S/D series resistance R
_SD
of the p- and n-MOSFET is reduced by ~25% and ~42% as compared with that of the transistors with conventional p/n junctions.