Improved Interfacial and Electrical Properties of Ge-Based Metal-Oxide-Semiconductor Capacitor With LaTaON Passivation Layer

The interfacial and electrical properties of Ge-based metal-oxide-semiconductor (MOS) capacitor with high-k gate dielectric of HfTiO and passivation interlayer of LaTaON are investigated. Experimental results show the Ge MOS with HfTiO/LaTaON gate-stacked dielectric exhibits low interface-state density (7.8 × 10¹¹ cm^-2 eV^-1), small gate-leakage current (7.88 × 10^-4 A cm^-2 at V_g - V_fb = 1 V), small capacitance equivalent thickness (1.1 nm), and large equivalent dielectric constant (27.7). X-ray photoelectron spectroscopy and transmission electron microscopy reveal that the improvements should be due to the fact that La/Ta-based oxide/oxynitride has excellent interface properties with Ge, and the LaTaON interlayer can effectively block the in-diffusion of oxygen and the out-diffusion of germanium, thus suppressing the growth of low-k GeO_x and intermixing between Ge and Hf.