High-performance germanium p-and n-MOSFETs with NiGe Source/Drain

In this paper, we report Ge p-and 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 ∼ 10⁵ and ∼2 × 10⁴ at |V| = 1V, respectively. Interface state densities D _it of Al₂O₃/GeO₂/Ge stack is improved to be around 10¹²/eV^-1 cm² 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~μ A\μm at (|V_GS}-V_T = 0.8) V and (|V_DS| = V is obtained, respectively, for p-and 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.