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 ~10⁵ and ~2 × 10⁴ at |V| = ±1 V, respectively. Interface state densities Dit 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 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.