Improvements of Interfacial and Electrical Properties for Ge MOS Capacitor with LaTaON Gate Dielectric by Optimizing Ta Content

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 \sim30% exhibit the best interfacial and electrical properties, including low interface-state density (7.6\times10^11 cm^-2 eV^-1), small gate-leakage current (8.32\times10^-5 A/cm^2) and large equivalent permittivity (22.46). The x-ray photoelectron spectroscopy results confirm that the least GeO_x is formed at the Ge surface for the sample with a Ta content of \sim30% due to the effective blocking role of Ta against O diffusion and the greatly improved hygroscopicity of LaON.