Interface characteristics of ZrO₂ high-k gate dielectrics on epitaxial Ge capacitor layers after thermal desorption of Ge native oxide and Ge nitridation

The authors report on interface characteristics of ZrO₂ high-k gate dielectrics on Ge epitaxial layers integrated on Si substrates. For surface passivation, thermal desorption of Ge native oxide and Ge nitridation processes is applied to epitaxial Ge capacitor layers. Metal-oxide-semiconductor capacitors exhibit excellent electrical characteristics with a gate leakage current density of 6 × 10^{- 7}-1 × 10^{- 6} A/cm² with a capacitance equivalent thickness of 1.5-1.3 nm at a gate voltage of 1 V. Thermal behavior of Ge native oxide and nitrided Ge layers is correlated with electrical characteristics.