High-k materials based on SrHfO3 and BaHfO3: A Hybrid Density Functional Theory Study

Abstract

High-dielectric-constant (high-k) materials are important as dielectric layers for computer processors to prevent unnecessary electrical current leakages. There is a fast-growing demand in the semiconductor industry for the exploration and integration of alternative high-k materials with the electronic device because the conventional dielectric material such as it gradually becomes difficult for SiO2 to satisfy the industrial need. There are many promising candidates for the high-k materials such as BaTiO3 and HfO2. Among these, ternary oxides (consisting of three elements and usually having perovskite crystal structure) can offer much better electrical properties than SiO2, thus providing potentially better solutions for the current-leakage problem. The previous experiments on the band structure and dielectric properties of SrHfO3 and BaHfO3 have shown their good potential for high-k materials. However, the theoretical understanding of these materials is still rare. In this paper, we have computed the electronic structure, optical and static dielectric constants of SrHfO3 and BaHfO3 by using hybrid-exchange density-functional theory. This work aims to provide a better understanding through accurate computational calculations of ternary oxides to prove its compatibility and superior material qualities for the future integration into semiconductor devices. A larger band gap (~ 10 eV) with comparable static dielectric constant with HfO2 (another good candidate for high-k dielectrics) has been suggested by our calculations for SrHfO3 and BaHfO3. The computed static dielectric constants for both materials are in agreement with the experimental results reported previously. Our calculations will provide a solid theoretical foundation for using Hf-bearing ternary oxides to tackle the future need of high-k materials.