Tunable Work Function and Surface Energy in Titanium Nitride (TiN) Thin Films through Quantum Well States

High work function metals are crucial in various semiconductor applications. Titanium nitride (TiN) is particularly noteworthy as a high work function material in metal gate structures, which significantly enhances the transistor performance and reliability in advanced semiconductor devices. In this study, we employ first-principles calculations to demonstrate that the TiN work function oscillates with thickness due to the quantum well state effect. Furthermore, we investigate the termination and surface dependence of the work function across different crystallographic orientations. We show that the work function can be enhanced to up to 8.04 eV for TiN(111) with N-termination at five monolayers (5 MLs). Our findings provide valuable insights for fine-tuning the high work function of TiN.