中文摘要：

Plasma treatment and 10% NH4OH solution rinsing were performed on a germanium（Ge） surface.It was found that the Ge surface hydrophilicity after O2 and Ar plasma exposure was stronger than that of samples subjected to N2 plasma exposure. This is because the thin Ge Ox film formed on Ge by O2 or Ar plasma is more hydrophilic than Ge Ox Ny formed by N2 plasma treatment. A flat（RMS < 0:5 nm） Ge surface with high hydrophilicity（contact angle smaller than 3°） was achieved by O2 plasma treatment, showing its promising application in Ge low-temperature direct wafer bonding.

英文摘要：

Plasma treatment and 10% NH_4OH solution rinsing were performed on a germanium（Ge） surface.It was found that the Ge surface hydrophilicity after O_2 and Ar plasma exposure was stronger than that of samples subjected to N_2 plasma exposure. This is because the thin Ge Ox film formed on Ge by O_2 or Ar plasma is more hydrophilic than Ge Ox Ny formed by N_2 plasma treatment. A flat（RMS 〈 0：5 nm） Ge surface with high hydrophilicity（contact angle smaller than 3°） was achieved by O_2 plasma treatment, showing its promising application in Ge low-temperature direct wafer bonding.