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The interfacial and electrical properties of high-k LaTaON gate dielectric Ge metal-oxide-semiconductor (MOS) capacitors with different tantalum (Ta) contents are investigated. Experimental results show that the Ge MOS capacitors with a Ta content of ∼30% exhibit the best interfacial and electrical properties, including low interface-state density (7.6 × 1011 cm−2 eV−1), small gate-leakage current (8.32 × 10−5 A/cm2) and large equivalent permittivity (22.46). The x-ray photoelectron spectroscopy results confirm that the least GeOx is formed at the Ge surface for the sample with a Ta content of ∼30% due to the effective blocking role of Ta against O diffusion and the greatly improved hygroscopicity of LaON.