Abstract
In this paper, oxidation of Ge surface by N2O plasma is presented and experimentally demonstrated. Results show that 1.0-nm GeO2 is achieved after 120-s N2O plasma oxidation at 300 °C. The GeO2/Ge interface is atomically smooth. The interface state density of Ge surface after N2O plasma passivation is about ∼ 3 × 1011 cm−2·eV−1. With GeO2 passivation, the hysteresis of metal—oxide—semiconductor (MOS) capacitor with Al2O3 serving as gate dielectric is reduced to ∼ 50 mV, compared with ∼ 130 mV of the untreated one. The Fermi-level at GeO2/Ge interface is unpinned, and the surface potential is effectively modulated by the gate voltage.