Optimization of N content for Higk-k LaTiON gate dielectric of Ge MOS capacitor

Thin LaTiON gate dielectric is deposited on Ge (100) substrate by reactive co-sputtering of La₂O₃ and Ti targets under different Ar/N₂ ratios of 24/3, 24/6, 24/12, and 24/18, and their electrical properties are investigated and compared. Results show that the LaTiON gate-dielectric Ge MOS capacitor prepared at an Ar/N₂ ratio of 24/6 exhibits highest relative permittivity, smallest capacitance equivalent thickness, and best electrical characteristics, including low interface-state density, small C-V hysteresis and low gate leakage current. This is attributed to the fact that a suitable N content in LaTiON can effectively suppress the growth of low-k GeO_x interfacial layer between LaTiON and Ge substrate.