Temperature-dependent admittance analysis of HfO₂ gate dielectrics on nitrogen- and sulfur-passivated Ge

In this work, we characterize MOS capacitors with HfO 2 gate dielectrics that utilize sulfur (S) passivation formed by pre-treatment of the Ge surface in an aqueous (NH 4 ) 2 S solution before HfO 2 deposition, and compare the results with those using the more-standard N-passivation. Using temperature-dependent admittance measurements, we find that the S-passivated samples have lower minimum D it and reduced flat-band shift, but also display larger accumulation dispersion and hysteresis than N-passivated samples. Results of admittance spectroscopy analysis also suggest that the energy distributions of the interface states are fundamentally different in the two sample types.